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nerdybill answered: 6949 problems
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Exponential-and-logarithmic-functions/731662: when logx=2logA-(1/2)logB, x is equal to
1 solutions

Answer 447235 by nerdybill(6951) About Me  on 2013-03-28 23:56:06 (Show Source):
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when logx=2logA-(1/2)logB, x is equal to
.
logx=2logA-(1/2)logB
logx = logA^2 - logB^(1/2)
logx = log(A^2/B^(1/2))
x = A^2/B^(1/2)
.
or,
x+=+A%5E2%2FB%5E%281%2F2%29
.
x+=+A%5E2%2Fsqrt%28B%29
.
x+=+A%5E2%2Fsqrt%28B%29%2A+sqrt%28B%29%2Fsqrt%28B%29
.
x+=+A%5E2%2Asqrt%28B%29%2FB



Quadratic-relations-and-conic-sections/730902: what is the equation of a circle with center (2,0) and radius 2 units?

1 solutions

Answer 446932 by nerdybill(6951) About Me  on 2013-03-26 20:49:51 (Show Source):
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what is the equation of a circle with center (2,0) and radius 2 units?
.
Equation of a circle:
(x-h)^2 + (y-k)^2 = r^2
where
(h,k) is the center
r is the radius
.
Plug in given data into:
(x-h)^2 + (y-k)^2 = r^2
(x-2)^2 + (y-0)^2 = 2^2
(x-2)^2 + y^2 = 4 (this is what they're looking for)


Unit_Conversion_Word_Problems/730829: 1 hose can fill a goldfish pond in 65 mins, and 2 hoses can the same pond in 40 mins. find how long it takes the second hose alone to fill the goldfish pond
1 solutions

Answer 446874 by nerdybill(6951) About Me  on 2013-03-26 17:05:19 (Show Source):
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1 hose can fill a goldfish pond in 65 mins, and 2 hoses can the same pond in 40 mins. find how long it takes the second hose alone to fill the goldfish pond
.
Let x = time (minutes) it takes for second hose alone
then
40(1/65 + 1/x) = 1
multiply both sides by 65x:
40(x + 65) = 65x
40x + 2600 = 65x
2600 = 25x
104 minutes = x


Travel_Word_Problems/730206: a person travels a distance of 72 km in 4 hours then his average speed is ?
1 solutions

Answer 446550 by nerdybill(6951) About Me  on 2013-03-25 06:50:08 (Show Source):
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divide 72 by 4 to get:
18 km/hr


Miscellaneous_Word_Problems/730192: The sum of the measures of the angles in any triangle is 180°. Jacqueline has a triangular area in her back yard where she intends to create a garden. If the largest angle is five times the smallest and the middle angle is 20° more than twice the smallest, find the measure of each angle. (It may help to draw the triangle and label each angle.)
1 solutions

Answer 446549 by nerdybill(6951) About Me  on 2013-03-25 06:47:33 (Show Source):
You can put this solution on YOUR website!
The sum of the measures of the angles in any triangle is 180°. Jacqueline has a triangular area in her back yard where she intends to create a garden. If the largest angle is five times the smallest and the middle angle is 20° more than twice the smallest, find the measure of each angle. (It may help to draw the triangle and label each angle.)
.
Let x = measure of smallest angle
then
5x = largest angle
2x+20 = middle angle
.
x + 5x + 2x+20 = 180
8x+20 = 180
8x = 160
x = 20 degrees (smallest angle)
.
largest angle:
5x = 5(20) = 100 degrees
.
middle angle:
2x+20 = 2(20)+20 = 40+20 = 60 degrees


Miscellaneous_Word_Problems/730161: A ball is thrown upward from the top of a building. The ball's height above the ground after T seconds is given by the function: h(t) = -16t^2+48t+32.
A. What is the initial height (i.e. the height of the building)?
B. How high did the ball go?
C. When does the ball hit the ground?
1 solutions

Answer 446516 by nerdybill(6951) About Me  on 2013-03-24 23:45:25 (Show Source):
You can put this solution on YOUR website!
A ball is thrown upward from the top of a building. The ball's height above the ground after T seconds is given by the function: h(t) = -16t^2+48t+32.
A. What is the initial height (i.e. the height of the building)?
initial height is when t=0:
h(t) = -16t^2+48t+32
h(0) = -16(0)^2+48(0)+32
h(0) = 32 feet
.
B. How high did the ball go?
vertex is at max:
time, at vertex:
t = -b/(2a)
t = -48/(2(-16))
t = -48/(-32)
t = 3/2
.
Height at t=3/2:
h(3/2) = -16(3/2)^2+48(3/2)+32
h(3/2) = -16(9/4)+24(3)+32
h(3/2) = -4(9)+24(3)+32
h(3/2) = -36+72+32
h(3/2) = 68 feet
.
C. When does the ball hit the ground?
set h(t) to zero and solve for t:
h(t) = -16t^2+48t+32
0 = -16t^2+48t+32
0 = t^2-3t-2
solve by applying the "quadratic formula" to get:
t = {3.56, -0.56}
throw out the negative solution (extraneous) leaving
t = 3.56 seconds
.
Details of quadratic formula follows:
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-3x%2B-2+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-3%29%5E2-4%2A1%2A-2=17.

Discriminant d=17 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--3%2B-sqrt%28+17+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-3%29%2Bsqrt%28+17+%29%29%2F2%5C1+=+3.56155281280883
x%5B2%5D+=+%28-%28-3%29-sqrt%28+17+%29%29%2F2%5C1+=+-0.56155281280883

Quadratic expression 1x%5E2%2B-3x%2B-2 can be factored:
1x%5E2%2B-3x%2B-2+=+1%28x-3.56155281280883%29%2A%28x--0.56155281280883%29
Again, the answer is: 3.56155281280883, -0.56155281280883. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-3%2Ax%2B-2+%29


Equations/729980: A lot is in the shape of a right triangle. The shorter leg measures 150m. The hypotenuse is 50m longer than the length of the longer leg. How long is the longer leg?
1 solutions

Answer 446381 by nerdybill(6951) About Me  on 2013-03-24 17:37:46 (Show Source):
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A lot is in the shape of a right triangle. The shorter leg measures 150m. The hypotenuse is 50m longer than the length of the longer leg. How long is the longer leg?
Let x = length (m) of longer leg
then
x+50 = length of hypotenuse
.
applying Pythagorean theorem:
150^2 + x^2 = (x+50)^2
150^2 + x^2 = (x+50)(x+50)
22500 + x^2 = x^2+100x+2500
22500 = 100x+2500
20000 = 100x
200 m = x (longer leg)


Polynomials-and-rational-expressions/729870: Please help me to solve this problem it's called division of polynomials(-9x3squared+3x2squared-15x)divided by (-3x)
1 solutions

Answer 446275 by nerdybill(6951) About Me  on 2013-03-24 11:02:18 (Show Source):
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(-9x3squared+3x2squared-15x)divided by (-3x)
.
%28-9x%5E3%2B3x%5E2-15x%29%2F%28-3x%29
.
we can "distribute" thus:
.
-9x%5E3%2F%28-3x%29+%2B+3x%5E2%2F%28-3x%29+-+15x%2F%28-3x%29
.
3x%5E2+%2B+3x%5E2%2F%28-3x%29+-+15x%2F%28-3x%29
.
3x%5E2+-+x+-+15x%2F%28-3x%29
.
3x%5E2+-+x+%2B+5


Distributive-associative-commutative-properties/729843: SOLVE THE PROBLEM L=NE/RT+NR FOR N
1 solutions

Answer 446273 by nerdybill(6951) About Me  on 2013-03-24 10:54:09 (Show Source):
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L=NE/RT+NR
factoring out an 'N' on the right side:
L=N(E/RT+R)
multiplying both sides by (RT+R):
L(RT+R) = NE
LR(T+1) = NE
dividing both sides by E:
LR(T+1)/E = N


Mixture_Word_Problems/729856: How many quarts of pure antifreeze must be added to 2 quarts of a 10% antifreeze solution to obtain a 40% antifreeze solution? and round to the nearest tenth as needed. My email is golittlediva@yahoo.com
1 solutions

Answer 446272 by nerdybill(6951) About Me  on 2013-03-24 10:49:33 (Show Source):
You can put this solution on YOUR website!
How many quarts of pure antifreeze must be added to 2 quarts of a 10% antifreeze solution to obtain a 40% antifreeze solution? and round to the nearest tenth as needed. My email is golittlediva@yahoo.com
.
Let x = amount (quarts) of pure antifreeze added
then
x + .10(2) = .40(x+2)
x + .20 = .40x+.80
x = .40x+.60
.60x = .60
x = 1.0 quart


Quadratic_Equations/729822: The diagonal of a rectangle is 1m less than twice the length of one of the sides. The other side is 5m long. What is the diagonal
1 solutions

Answer 446252 by nerdybill(6951) About Me  on 2013-03-24 04:15:53 (Show Source):
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The diagonal of a rectangle is 1m less than twice the length of one of the sides. The other side is 5m long. What is the diagonal
.
Let d = diagonal
then
d/2 = length of one side
.
applying Pythagorean theorem:
d^2 = (d/2)^2 + 5^2
d^2 = d^2/4 + 25
4d^2 = d^2 + 100
3d^2 = 100
d^2 = 100/3
d = sqrt(100/3)
d = sqrt(100)/sqrt(3)
d = 10/sqrt(3)
d = 10/sqrt(3) * sqrt(3)/sqrt(3)
d = 10sqrt(3)/3 meters


Percentage-and-ratio-word-problems/729819: Gina has to spend 3/10 of her weekly income on food and board and 1/5 on travel to and from university and 1/8 on text books. What fraction of her income does she spend?
If Gina can save one third of her remaining income what fraction of her income does she save?

1 solutions

Answer 446251 by nerdybill(6951) About Me  on 2013-03-24 04:10:29 (Show Source):
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Gina has to spend 3/10 of her weekly income on food and board and 1/5 on travel to and from university and 1/8 on text books. What fraction of her income does she spend?
3/10 + 1/5 + 1/8
12/40 + 8/40 + 5/40
(12+8+5)/40
25/40
5/8 (answer)
.
If Gina can save one third of her remaining income what fraction of her income does she save?
Amount remaining: 1-5/8 = 3/8
.
(1/3)(3/8)
3/24
1/8 (answer)


Linear-systems/729763: Please help me solve this problem:
One music company charges a $15 membership fee and $0.75 each to download a song. Another company charges $.90 per song to download a song (no membership fee).
For what number of songs will both companies charge the same amount? How much will it cost when each company charges the same amount? Justify your answer using mathematics.
1 solutions

Answer 446250 by nerdybill(6951) About Me  on 2013-03-24 04:04:43 (Show Source):
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One music company charges a $15 membership fee and $0.75 each to download a song. Another company charges $.90 per song to download a song (no membership fee).
.
Let x = number of songs downloaded
then
1st company:
.75x + 15
2nd company:
.90x
.
For what number of songs will both companies charge the same amount?
set the two equations equal to each other and solve for x:
.75x + 15 = .90x
15 = .15x
15/.15 = x
100 songs = x
.
How much will it cost when each company charges the same amount?
plug above into:
.90x
.90(100)
$90


Polynomials-and-rational-expressions/729774: Help find the factory
y^3-11y^2+28y
1 solutions

Answer 446249 by nerdybill(6951) About Me  on 2013-03-24 04:00:29 (Show Source):
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y^3-11y^2+28y
y(y^2-11y+28)
y(y-4)(y-7)


Miscellaneous_Word_Problems/729821: PLEASE, SOMEONE HELP ME !!!
Two mortgage companies want to hire you as a consultant. Firm A offers you $60 plus rate of $50 per hour. Firm B offers you a flat rate of $65 per hour.
A) Find the "break-even" point - the point where both companies would pay the same amount.
B) If you work for 10 hours, which firm would give you the most money?
*You "Like" to solve this wrd. problem, and I will "Like" you on your website and Facebook . . Excellent !!!

1 solutions

Answer 446248 by nerdybill(6951) About Me  on 2013-03-24 03:54:32 (Show Source):
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Two mortgage companies want to hire you as a consultant. Firm A offers you $60 plus rate of $50 per hour. Firm B offers you a flat rate of $65 per hour.
.
Let x = hours worked
then
Firm A:
60x+50
Firm B:
65x
.
A) Find the "break-even" point - the point where both companies would pay the same amount.
"break-even" is when they amount earned is the same for either Firm:
60x+50 = 65x
50 = 5x
10 hours = x
.
B) If you work for 10 hours, which firm would give you the most money?
From part A, working 10 hours is the "break-even" point.
This is when both firms will pay exactly the same amount.
.
You could plug it in and verify:
Firm A:
60x+50 = 60(10)+50 = 600+50 = $650
Firm B:
65x
65x = 65(10) = $650
Answer: both firms will give exactly the same amount


Quadratic_Equations/729712: I need to find the equation of the quadratic function. I need to express my answer in the form P(x)=ax^+bx+c. The vertex is (-1,-4); through (5,104). I have no idea how to do this. Please help! Thanks!
1 solutions

Answer 446205 by nerdybill(6951) About Me  on 2013-03-23 20:45:06 (Show Source):
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I need to express my answer in the form P(x)=ax^+bx+c. The vertex is (-1,-4); through (5,104).
.
"Vertex form" of quadratic:
y = a(x-h)^2 + k
where
(h,k) is the vertex
.
since the problem gives you the vertex (-1,-4) and one point (5,104) plug it in to the vertex form and solve for 'a':
y = a(x-h)^2 + k
104 = a(5-(-1))^2 + (-4)
104 = a(5+1)^2 - 4
104 = a(6)^2 - 4
104 = a(36) - 4
108 = a(36)
3 = a
.
Now, our vertex form is:
y = a(x-h)^2 + k
y = 3(x-(-1))^2 + (-4)
y = 3(x+1)^2 - 4
.
we now convert the above to the correct form:
y = 3(x+1)^2 - 4
y = 3(x+1)(x+1) - 4
y = 3(x^2+2x+1) - 4
y = 3x^2+6x+3 - 4
y = 3x^2+6x-1
so,
P(x)=3x^2+6x-1 (answer)





Rate-of-work-word-problems/729664: It takes Bob 4 hours longer to repair a car than it takes Ken. Working together, they can complete the job in 1.5 hours. How long would each of them take working alone.
1 solutions

Answer 446160 by nerdybill(6951) About Me  on 2013-03-23 14:02:19 (Show Source):
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It takes Bob 4 hours longer to repair a car than it takes Ken. Working together, they can complete the job in 1.5 hours. How long would each of them take working alone.
.
Let x = time (hours) it takes ken to do job alone
then
x+4 = time it takes bob
.
1.5(1/(x+4) + 1/x) = 1
multiplying both sides by x(x+4):
1.5(x + x+4) = x(x+4)
1.5(2x+4) = x^2+4x
3x+6 = x^2+4x
6 = x^2+x
0 = x^2+x-6
0 = (x+3)(x-2)
x = {-3, 2}
throw out negative solution (extraneous) leaving:
x = 2 hours (Ken)
.
Bob:
x+4 = 2+4 = 6 hours


Money_Word_Problems/729619: 1)find the break-even point for the firm whose cost function C and revenue function R are given. round the intermediate calculation to nearest integer.
C(x)=210x+20,000 ; R(x)=240x
1 solutions

Answer 446064 by nerdybill(6951) About Me  on 2013-03-23 10:08:15 (Show Source):
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1)find the break-even point for the firm whose cost function C and revenue function R are given. round the intermediate calculation to nearest integer.
C(x)=210x+20,000 ; R(x)=240x
.
Breakeven is when
C(x) = R(x)
210x+20000 = 240x
20000 = 30x
666.66 = x
rounded to nearest integer:
667 = x


Miscellaneous_Word_Problems/729606: Hi I need help on this question
Sasha is planning to put a patio around her new pool which has dimensions of 20m by 30m. she wants the patio to have a uniform width,x,and to surround the entire pool. Her budget is $6000 and she knows it will cost $10/m^2 to construct the patio. How wide can she afford for the patio to be?
1 solutions

Answer 446062 by nerdybill(6951) About Me  on 2013-03-23 10:06:09 (Show Source):
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Sasha is planning to put a patio around her new pool which has dimensions of 20m by 30m. she wants the patio to have a uniform width,x,and to surround the entire pool. Her budget is $6000 and she knows it will cost $10/m^2 to construct the patio. How wide can she afford for the patio to be?
.
Let x = width of patio
then
area of "pool and patio" is:
(2x+20)(2x+30)
4x^2+60x+40x+600
.
our equation:
10((2x+20)(2x+30)- (20)(30))= 6000
10(4x^2+60x+40x+600 - 600)= 6000
10(4x^2+100x)= 6000
(4x^2+100x)= 600
4x^2+100x-600 = 0
x^2+25x-150 = 0
x^2+25x-150 = 0
(x+30)(x-5) = 0
x = {-30, 5}
throw out the negative solution (extraneous) leaving
x = 5 m


Travel_Word_Problems/729590: James left home and travelled towards the moumtains.Lisa left 2.1 hours later travelling 35 km/h faster in an effort to catch him. After 1.2 hours Lisa finally caught up with him.What was James average speed?
1 solutions

Answer 446044 by nerdybill(6951) About Me  on 2013-03-23 06:42:40 (Show Source):
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James left home and travelled towards the moumtains.Lisa left 2.1 hours later travelling 35 km/h faster in an effort to catch him. After 1.2 hours Lisa finally caught up with him.What was James average speed?
.
Let x = james average speed (km/h)
then
x+35 = lisa's average speed (km/h)
.
1.2 hours = Lisa's driving time
1.2+2.1 = 3.3 hours = James' driving time
.
our equation
1.2(x+35) = 3.3x
1.2x+42 = 3.3x
42 = 2.1x
42/2.1 = x
20 mph = x


Rate-of-work-word-problems/729529: Working together, it takes two computers 15 minutes to send out a company’s email. If it takes the slower computer 60 minutes to do the job on its own, how long will it take the faster computer to do the job on its own?
1 solutions

Answer 446043 by nerdybill(6951) About Me  on 2013-03-23 06:37:24 (Show Source):
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Working together, it takes two computers 15 minutes to send out a company’s email. If it takes the slower computer 60 minutes to do the job on its own, how long will it take the faster computer to do the job on its own?
.
Let x = time (minutes) it takes faster computer to do job alone
then
15(1/x + 1/60) = 1
multiplying both sides by 60x:
15(60 + x) = 60x
900 + 15x = 60x
900 = 45x
20 minutes = x


logarithm/728568: Help me please! I'm stuck on this problem: 3^2x=6561
1 solutions

Answer 445504 by nerdybill(6951) About Me  on 2013-03-20 14:52:15 (Show Source):


logarithm/728456: log6(x-1)+log6(x+4)=2
1 solutions

Answer 445419 by nerdybill(6951) About Me  on 2013-03-20 09:51:41 (Show Source):
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log6(x-1)+log6(x+4)=2
log6(x-1)(x+4)=2
(x-1)(x+4)=6^2
x^2+3x-4=36
x^2+3x-40=0
(x+8)(x-5) = 0
x = {-8,5}
throw out the -8 (extraneous) leaving:
x = 5


Mixture_Word_Problems/728460: how many liters of a 30% saline solution must be mixed with a 40% saline solution to obtain 25 liters of a 32% saline solution?
1 solutions

Answer 445418 by nerdybill(6951) About Me  on 2013-03-20 09:49:20 (Show Source):
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how many liters of a 30% saline solution must be mixed with a 40% saline solution to obtain 25 liters of a 32% saline solution?
.
Let x = amount (liters) of 30%
then
25-x = amount (liters) of 40%
.
.30x + .40(25-x) = .32(25)
.30x + 10-.40x = 8
10-.10x = 8
-.10x = -2
x = 20 liters (of 30%)
.
amount of 40%:
25-x = 25-20 = 5 liters


Miscellaneous_Word_Problems/728349: A rocket shot into the aire has a height of s= 128t - 16t^2 feet, where t is the number of seconds after the rocket is shot. During what time after the rocket is shot is it atleast 240 feet high??
1 solutions

Answer 445378 by nerdybill(6951) About Me  on 2013-03-20 00:00:40 (Show Source):
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A rocket shot into the aire has a height of s= 128t - 16t^2 feet, where t is the number of seconds after the rocket is shot. During what time after the rocket is shot is it atleast 240 feet high??
.
set s to 240 and solve for t:
s= 128t - 16t^2
240 = 128t - 16t^2
15 = 8t - t^2
t^2 + 15 = 8t
t^2 - 8t + 15 = 0
(t-3)(t-5) = 0
t = {3, 5}
answer: the entire time between 3 seconds and 5 seconds


test/728079: Hugo has $20 . He spends n dollars. How much does he have left ?
1 solutions

Answer 445297 by nerdybill(6951) About Me  on 2013-03-19 15:37:46 (Show Source):
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Hugo has $20 . He spends n dollars. How much does he have left ?
.
He has 20-n dollars left.


Rate-of-work-word-problems/728073: craig and jim,working together, can clean the house in 2 hours. Working alone, jim takes twice as long as craig. How long does it take craig to clean the house alone?
1 solutions

Answer 445293 by nerdybill(6951) About Me  on 2013-03-19 15:10:54 (Show Source):
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craig and jim,working together, can clean the house in 2 hours. Working alone, jim takes twice as long as craig. How long does it take craig to clean the house alone?
.
Let x = time (hours) it takes Craig to clean the house alone
then
2x = time (hours) it takes Jim to clean the house alone
.
The equation:
2(1/x + 1/(2x)) = 1
multiplying both sides by 2x:
2(2 + 1) = 2x
2(3) = 2x
6 = 2x
3 hours = x (Time it takes Craig)


Quadratic_Equations/728062: answer the question below about the quadratic function g(x) =2x^2+8x+12
1) does the function have a minium or maxium value
2) what is the funtion mininum or maxium value
3) where does the minimum or maxium occur
1 solutions

Answer 445292 by nerdybill(6951) About Me  on 2013-03-19 15:08:25 (Show Source):
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answer the question below about the quadratic function g(x) =2x^2+8x+12
1) does the function have a minium or maxium value
Because the leading coefficient is POSITIVE, the parabola opens downwards -- thus the function has a maximum.
.
It is easier to answer part 3) first:
3) where does the minimum or maxium occur
this is the "axis of symmetry":
x = -b/(2a)
x = -8/(2*2)
x = -8/(4)
x = -2
.
2) what is the funtion mininum or maxium value
plug -2 into the the equation to find the max:
g(x) =2x^2+8x+12
g(-2) =2(-2)^2+8(-2)+12
g(-2) =2(4)+(-16)+12
g(-2) =8-16+12
g(-2) =-8+12
g(-2) = 4


Quadratic_Equations/728070: write the quadratic equation whose roots are -4 and -5 and whose leading coefficient is 5 use the letter x to represent the variable
1 solutions

Answer 445290 by nerdybill(6951) About Me  on 2013-03-19 15:02:48 (Show Source):
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write the quadratic equation whose roots are -4 and -5 and whose leading coefficient is 5 use the letter x to represent the variable
.
If roots are -4 and -5, then the factors are
(x+4) and (x+5)
.
if you want the leading coefficient also, we multiply it altogether to get the "quadratic equation":
5(x+4)(x+5)
5(x^2+5x+4x+20)
5(x^2+9x+20)
5x^2+45x+100


Numbers_Word_Problems/727388: how can i get the consucative even odd digit number
1 solutions

Answer 445081 by nerdybill(6951) About Me  on 2013-03-18 03:37:43 (Show Source):
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how can i get the consucative even odd digit number
.
for "even consecutive" numbers:
Let x = first even number
then
x+2 = second even consecutive number
.
for "odd consecutive" numbers:
Let x = first odd number
then
x+2 = second odd consecutive number
.
Apply the above to your problems. It will work out...


Miscellaneous_Word_Problems/726646: Choose the expression or equation that is equivalent to the one given.

x-5 =9
Possible answers:
A) logx9=5
B) -5 logx=log9
C) logx(-5)=9
D) logx9=-5
E) log9 x=-5
1 solutions

Answer 444755 by nerdybill(6951) About Me  on 2013-03-16 08:18:45 (Show Source):
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answer would be "B"
.
x%5E%28-5%29+=9
.
take the log of both sides:
.
log%28x%5E%28-5%29%29+=+log%289%29
.
from "logarithm rules":
%28-5%29log%28x%29+=+log%289%29