See tutors' answers!

Algebra ->  Tutoring on algebra.com -> See tutors' answers!      Log On


   
By Tutor
 | By Problem Number | 

Tutor:
New! Get regular updates about newly solved problems via algebra.com's RSS system.

Recent problems solved by 'all'

all answered: 299 problems
Jump to solutions: 0..29 , 30..59 , 60..89 , 90..119 , 120..149 , 150..179 , 180..209 , 210..239 , 240..269 , 270..299, >>Next

Linear-equations/751777: I have a problem on a homework assignment. The problem says: A farmhouse shelters 10 animals. Some are pigs and some are ducks. Together, there are 36 legs. How many of each are there?

1 solutions

Answer 457394 by JoeTaxpayer(116) About Me  on 2013-05-22 22:12:19 (Show Source):
You can put this solution on YOUR website!
4P+2D=36 i.e. 4 times the number of pigs is the number of pig-feet, 2D = duck-feet
P+D=10 ten animals total.
Multiply second equation by 4:
4P+4D=40
4P+2D=36 (and subtract first equation.
2D=4
2 ducks, 8 pigs. 10 animals.
4 duck feet + 32 pig-feet, total 36 feet.


Surface-area/751782: The height of the cylinder is three times the diameter of the base. The surface area of the cylinder is 126. What is the radius of the base
1 solutions

Answer 457393 by josgarithmetic(1517) About Me  on 2013-05-22 22:11:34 (Show Source):
You can put this solution on YOUR website!
Say the diameter is d and the radius is d%2F2.
Let h= height of the cylinder.

h=3%2Ad

circumference is the LENGTH of the rounded side. This circumference is 2%2Api%2A%28d%2F2%29, or
circumference is d%2Api

The surface area then is h%2A%28d%2Api%29=3%2Ad%2A%28d%2Api%29=3d%5E2%2Api
and you were given in the description:
highlight%283d%5E2%2Api=126%29.
Solving for d is uncomplicated.


Quadratic-relations-and-conic-sections/751759: What conic section describes the graph of the equation below?
(x + 7)^2 + (y - 4)^2 = 64
2 solutions

Answer 457392 by JoeTaxpayer(116) About Me  on 2013-05-22 22:08:01 (Show Source):
You can put this solution on YOUR website!
It's a circle.
Its center is at (-7,4) and it had a radius of 8


Answer 457383 by tommyt3rd(545) About Me  on 2013-05-22 21:17:53 (Show Source):
You can put this solution on YOUR website!
This is a circle centered at C(-7,4) with radius r=8

:)


Equations/751784: (6p + 11)(6p - 11)
Find the product.

1 solutions

Answer 457391 by stanbon(57346) About Me  on 2013-05-22 22:05:53 (Show Source):
You can put this solution on YOUR website!
(6p + 11)(6p - 11)
----
= 36p^2 - 121
======================
Cheers,
Stan H.
======================


Quadratic_Equations/751745: Solve: 16x^2-72x=-85
Not sure if I'm suppose to factor or use the quadratic equation? Help would be appreciated! :)
1 solutions

Answer 457390 by josmiceli(9678) About Me  on 2013-05-22 22:04:58 (Show Source):
You can put this solution on YOUR website!
+16x%5E2-72x=-85+
I don't know which method they want you to use, but
I can try completing the square
---------------------
First, divide both sides by +16+
+x%5E2+-+%289%2F2%29%2Ax+=+-85%2F16+
--------------------------
Take 1/2 of the coefficient of +x+,
square it, and add it to both sides
+x%5E2+-+%289%2F2%29%2Ax+%2B+%289%2F4%29%5E2+=+-85%2F16+%2B+%289%2F4%29%5E2+
+x%5E2+-+%289%2F2%29%2Ax+%2B+81%2F16+=+-85%2F16+%2B+81%2F16+
+x%5E2+-+%289%2F2%29%2Ax+%2B+81%2F16+=+-4%2F16+
+%28+x+-+9%2F4+%29%5E2+=+%28+1%2F2%29%5E2+%2A+i%5E2+
Take the square root of both sides
+x+-+9%2F4+=+%281%2F2%29%2Ai+
+x+=+%28+9+%2B+2i+%29+%2F+4+
and, also
+x+=+%28+9+-+2i+%29+%2F+4+
---------------------
Here's the plot:
+graph%28+500%2C+500%2C+-2%2C+5%2C+-2%2C+8%2C+16x%5E2+-+72x+%2B+85+%29+
Since it doesn't contact the x-axis, there are no real roots


Rate-of-work-word-problems/751778: George and Stanley are building a stone fence. They can complete the fence together in 8 hours, and George can complete it is 24 hours working alone. If they work together for 6 hours, then Stanley goes to the pub for a pint, how much longer must George work to finish the fence?
1 solutions

Answer 457389 by stanbon(57346) About Me  on 2013-05-22 22:03:22 (Show Source):
You can put this solution on YOUR website!
George and Stanley are building a stone fence. They can complete the fence together in 8 hours, and George can complete it is 24 hours working alone.
----
George & Stan together rate::: 1/8 job/hr
George rate::::: 1/24 job/hr
----------
If they work together for 6 hours, then Stanley goes to the pub for a pint, how much longer must George work to finish the fence?
-----
6(1/8) + x/24 = 1 job
-----
3/4 + x/24 = 1
--------
18 + x = 24
x = 6 hrs. (Time George needs to finish)
===================
Cheers,
Stan H.

------


Trigonometry-basics/751753: find all the zeros, real, and non real, of the polynomial p(x) = x^3 + 7x
1 solutions

Answer 457388 by tommyt3rd(545) About Me  on 2013-05-22 22:01:40 (Show Source):


Expressions-with-variables/751423: A man flies a small airplane from Fargo to Bismarck, North Dakota --- a distance of 180 miles. Because he is flying into a head wind, the trip takes him 2 hours. On the way back, the wind is still blowing at the same speed, so the return trip takes only 1 hour 12 minutes. What is his speed in still air, and how fast is the wind blowing?
His speed equals--
The wind speed equals--
1 solutions

Answer 457387 by ankor@dixie-net.com(15652) About Me  on 2013-05-22 21:56:36 (Show Source):
You can put this solution on YOUR website!
A man flies a small airplane from Fargo to Bismarck, North Dakota --- a
distance of 180 miles.
Because he is flying into a head wind, the trip takes him 2 hours.
On the way back, the wind is still blowing at the same speed, so the
return trip takes only 1 hour 12 minutes.
What is his speed in still air, and how fast is the wind blowing?
:
Change 1 hr 12 min: 1 + 12/60 = 1.2 hrs
:
Let s = his speed in still air
Let w = speed of the wind
then
(s-w) = effective speed against the wind
and
(s+w) = effective speed with the wind
:
Write a distance equation for each way; dist = time * speed
2(s - w) = 180
1.2(s+w) = 180
Simplify both equations, divide the 1st eq by 2, the 2nd eq by 1.2; results:
s - w = 90
s + w = 150
-------------addition eliminates w, find s
2s = 240
s = 240/2
s = 120 mph is the speed in still air
Find w
s + w = 150
120 + w = 150
w = 150 - 120
w = 30 mph is the speed of the wind
:
Check in 1st original equation
2(120-30) = 180
2(90) = 180


Linear-equations/751776: Determine whether these equations are parallel, perpendicular, or neither.
8x=5y+3
-24x=15y+3
Solve: 1/4x-1; (20, ) ( ,-3) I need to find the missing numbers.
Thank you.
1 solutions

Answer 457386 by stanbon(57346) About Me  on 2013-05-22 21:51:06 (Show Source):
You can put this solution on YOUR website!
Determine whether these equations are parallel, perpendicular, or neither.
8x=5y+3
-24x=15y+3
-----
y = (8/5)x - (3/5)
y = (-8/5)x - (1/5)
------
The slopes are (8/5) and (-8/5)
The lines are not parallel or perpendicular.
-------------------
Cheers,
Stan H.
==========================


percentage/751772: Tracey paid $190 for an item that was originally priced at $290. What percent of the original price did Tracey pay?

2 solutions

Answer 457385 by stanbon(57346) About Me  on 2013-05-22 21:44:00 (Show Source):
You can put this solution on YOUR website!
Tracey paid $190 for an item that was originally priced at $290. What percent of the original price did Tracey pay?
----------
x/100 = 190/290
x = 100(190/290)
x = 65.52%
------------------------
Cheers,
Stan H.


Answer 457384 by josmiceli(9678) About Me  on 2013-05-22 21:38:58 (Show Source):
You can put this solution on YOUR website!
+%28+190%2F290+%29%2A100+=+65.52+
$190 is 65.52% of $290


Coordinate-system/751689: Determine whether the lines x-5y=15 and -5x-y+2=0 are parallel, perpendicular, or neither.
I really need help with this one. Kim
2 solutions

Answer 457382 by MathTherapy(1424) About Me  on 2013-05-22 21:14:18 (Show Source):
You can put this solution on YOUR website!

Determine whether the lines x-5y=15 and -5x-y+2=0 are parallel, perpendicular, or neither.
I really need help with this one. Kim

x - 5y = 15 has a slope of 1%2F5, while - 5x - y + 2 = 0 has a slope of 5.

Since these two slopes are negative reciprocals of each other: 1%2F5 and -+%285%2F1%29, then the slopes are perpendicular to each other.


Answer 457367 by tommyt3rd(545) About Me  on 2013-05-22 19:08:10 (Show Source):
You can put this solution on YOUR website!
x-5y=15 has


m%5B1%5D=-B%2FA=-%28-5%29%2F1=5



and -5x-y+2=0 has


m%5B2%5D=-%28-1%29%2F%28-5%29=-1%2F5


and so

m%5B1%5Dm%5B2%5D=-1

they are perpendicular

:)


Permutations/751761: A die is rolled four times. Find P(four of the same number)
1 solutions

Answer 457381 by JoeTaxpayer(116) About Me  on 2013-05-22 21:13:27 (Show Source):
You can put this solution on YOUR website!
it's 1 in 6^3 or 1 in 216.
Why not 1 in 6^4?
It would be that if you asked the chances of 4 rolls of a particular number, but here it's just the same, so the first roll is 'free.' only the next three rolls must match.


Exponential-and-logarithmic-functions/751743: how would I solve log(5x+7)=2??

thanks!
1 solutions

Answer 457380 by tommyt3rd(545) About Me  on 2013-05-22 21:07:37 (Show Source):


Travel_Word_Problems/751437: 5 hens lay 6 eggs every 2 days.How many eggs will 25 chickens lay in 40 days?


1 solutions

Answer 457379 by ankor@dixie-net.com(15652) About Me  on 2013-05-22 20:28:56 (Show Source):
You can put this solution on YOUR website!
5 hens lay 6 eggs every 2 days.
Find the number of hen-days per egg
%28%285%2A2%29%29%2F6 = 5%2F3 hen-days per egg
:
How many eggs will 25 chickens lay in 40 days?
Invert the dividing fraction and multiply
(25*40) * 3%2F5 = 600 eggs


Sequences-and-series/751737: A side of an equilateral triangle is 10 cm. the midpoints of its sides are joined to form an inscribed equilateral triangle, and this process is continued. Find the sum of the perimeters of the triangles if the process is continued without end.
1 solutions

Answer 457378 by reviewermath(522) About Me  on 2013-05-22 20:17:42 (Show Source):
You can put this solution on YOUR website!
Perimeter of first triangle: 30 cm
second triangle: 15 cm
third triangle: 7.5 cm
...
nth triangle: 30%280.5%29%5E%28n+-+1%29
...
The sum of an infinite geometric series with first term a%5B1%5D and common ratio r is a%5B1%5D%2F%281+-+r%29 provided |r| < 1.
sum%2830%280.5%29%5E%28n+-+1%29%2C+n=+1%2C+infinity%29 = 30%2F%281+-+0.5%29 = highlight%2860%29 cm.


Probability-and-statistics/751665: ``During a drug trial for a new anitbotic, 45% of the people woh were given the drug experienced dizziness.
Assume a sample size of 15 patients..

Find the probability that less than 6 patients experienced dizziness.
Find the probability that at least 7 patients experienced dizziness.
Find the probability that at most 4 patients did NOT experience dizziness.
1 solutions

Answer 457377 by reviewermath(522) About Me  on 2013-05-22 20:00:33 (Show Source):
You can put this solution on YOUR website!

Find the probability that less than 6 patients experienced dizziness.
X ~ Binomial(15, 0.45)
P(X < 6) = sum%28%28matrix%282%2C1%2C15%2Cx%29%29%280.45%5Ex%29%280.55%5E%2815+-+x%29%29%2Cx+=+0%2C5%29 = highlight%280.26076%29

Find the probability that at least 7 patients experienced dizziness.
X ~ Binomial(15, 0.45)
P(X ≥ 7) = = highlight%280.54784%29

Find the probability that at most 4 patients did NOT experience dizziness.
X ~ Binomial(15, 0.55)
P(X ≤ 4) = sum%28%28matrix%282%2C1%2C15%2Cx%29%29%280.55%5Ex%29%280.45%5E%2815+-+x%29%29%2Cx+=+0%2C4%29 = highlight%280.02547%29


Trigonometry-basics/750407: Find all solutions in the interval o and 2pi
1.) Cos^2x+ sinx +1= 0
1 solutions

Answer 457376 by lwsshak3(6505) About Me  on 2013-05-22 19:59:13 (Show Source):
You can put this solution on YOUR website!
Find all solutions in the interval o and 2pi
1.) Cos^2x+ sinx +1= 0
1-sin^2(x)+sin(x)+1=0
sin^2(x)-sin(x)-2=0
(sin(x)-2)(sin(x)+1)=0
..
sin(x)=2 (reject, -1 ≤ sinx ≤ 1)
sin(x)=-1
x=3π/2


Polynomials-and-rational-expressions/751675: y^3+125.. please factor completely... if its prime that is also one of the options on my question. Thank you
1 solutions

Answer 457375 by reviewermath(522) About Me  on 2013-05-22 19:42:49 (Show Source):
You can put this solution on YOUR website!
Factoring the Sum of Two Cubes:
Step 1: Get the binomial factor
Cube root of the first term: y
Cube root of the second term: 5
The binomial factor is y + 5
Step 2: Get the trinomial factor
Square of the first term of the binomial factor: y%5E2
Negative Product of the first and second term of the binomial factors = -5y
Square of the second term of the binomial factor: 25
The trinomial factor is y%5E2+-+5y+%2B+25
Step 3: The factored form of y%5E3+%2B+125 is highlight%28%28y+%2B+5%29%28y%5E2+-+5y+%2B+25%29%29.


Polynomials-and-rational-expressions/751720: My teacher has a final in algebra one for us tomorrow. On the test are fractions. I am terrible at fractions. I need help on solving rational equations. I have no clue how to solve this. The question is -6x +3x over 5 devided by 4x-8 over 25
1 solutions

Answer 457374 by josgarithmetic(1517) About Me  on 2013-05-22 19:42:11 (Show Source):
You can put this solution on YOUR website!
-6x +3x over 5 devided by 4x-8 over 25
GIVEN: highlight%28%28%28-6x%2B3x%29%2F5%29%2F%28%284x-8%29%2F25%29%29
%28%28-6x%2B3%29%2F5%29%2A%2825%2F%284x-8%29%29
%28%28-6x%2B3%29%2Fcross%285%29%29%2A%28cross%285%29%285%29%2F%284x-8%29%29

highlight%285%28-6x%2B3%29%2F%284x-8%29%29 about as simple as you can make it but you can rewrite to bring the negative term in numerator away from the left:
highlight%285%283-6x%29%2F%284x-8%29%29


Trigonometry-basics/751287: Simplify: 1-sin^2((pi/2)-x)
1 solutions

Answer 457373 by lwsshak3(6505) About Me  on 2013-05-22 19:36:22 (Show Source):
You can put this solution on YOUR website!
1-sin^2((pi/2)-x)
sin(π/2-x)=cos(x)
1-sin^2((pi/2)-x)=1-cos^2(x)=sin^2(x)


Quadratic-relations-and-conic-sections/751709: Write an equation for the circle with the endpoints of the diameter at (-6,4) and (4,8)
1 solutions

Answer 457372 by reviewermath(522) About Me  on 2013-05-22 19:33:57 (Show Source):
You can put this solution on YOUR website!
First, get the length of the diameter by computing the
distance between the points (-6, 4) and (4, 8).
Using the distance formula:
d = sqrt%28%288+-+4%29%5E2+%2B+%284+-+%28-6%29%29%5E2%29%29
= sqrt%28116%29
= 2sqrt%2829%29
The length of the radius is half the length of the diameter.
r = %281%2F2%29%28d%29 = sqrt%2829%29.
Next, we get the coordinates of the center of the circle by
computing the midpoint of the diameter with endpoints (-6,4) and (4,8).
Using the midpoint formula:
center = (%28-6+%2B+4%29%2F2, %284+%2B+8%29%2F2)
= (-1, 6)
The equation of the circle with center (h,k) and radius r is
%28x+-+h%29%5E2+%2B+%28y+-+k%29%5E2+=+r%5E2, the center is (h,k) = (-1,6) and radius, r = sqrt%2829%29
Equation: highlight%28%28x+%2B+1%29%5E2+%2B+%28y+-+6%29%5E2+=+29%29



Polynomials-and-rational-expressions/751702: im preparing for a test and there will be question like this on there and im really confused can you show me how to do it? [x/(x-4)+6/(x+4)]÷3/(2x^2-32)
1 solutions

Answer 457371 by josgarithmetic(1517) About Me  on 2013-05-22 19:33:21 (Show Source):
You can put this solution on YOUR website!
Division by a number means multiplication by its reciprocal. You then have
%28x%2F%28x-4%29%2B6%2F%28x%2B4%29%29%2A%282x%5E2-32%29%2F3

%28x%28x%2B4%29%2B6%2A%28x-4%29%29%2F%28%28x-4%29%28x%2B4%29%29%2A%282x%5E2-32%29%2F3
%28x%28x%2B4%29%2B6%2A%28x-4%29%29%2F%28%28x-4%29%28x%2B4%29%29%2A%282%28x%5E-16%29%29%2F3


%28x%28x%2B4%29%2B6%28x-4%29%29%282%2F3%29
which can be finished multiplying whatever remains undone in the numerator and continuing simplifying, combining like-terms according to what's found.


Trigonometry-basics/751257: Can you help me solve the equations for x, if 0is less than equal to x is less than equal to 2pi.
a) 8cos^2x=4
1 solutions

Answer 457370 by lwsshak3(6505) About Me  on 2013-05-22 19:30:25 (Show Source):
You can put this solution on YOUR website!
solve the equations for x, if 0is less than equal to x is less than equal to 2pi.
a) 8cos^2x=4
cos^2(x)=4/8=1/2
cos(x)=1/√2=√2/2
x=π/4, 3π/4 (in Q1 and Q2 where sin>0)


Trigonometry-basics/751467: Complete the identity.
1). cos θ - cos θ sin^2 θ = ?
2). (1 / cos^2 θ) - (1 / cot^2 θ) = ?

1 solutions

Answer 457369 by lwsshak3(6505) About Me  on 2013-05-22 19:24:49 (Show Source):
You can put this solution on YOUR website!
Complete the identity.
1). cos θ - cos θ sin^2 θ = ?
cos%28x%291-sin%5E2%28x%29=cos%28x%29cos%5E2%28x%29=cos%5E3%28x%29
2). (1 / cos^2 θ) - (1 / cot^2 θ) = ?
%281%2Fcos%5E2%28x%29%29-%281%2Fcot%5E2%28x%29%29=1%2Fcos%5E2%28x%29-tan%5E2%28x%29%29


Equations/751711: what is 5(d+4) = 7(d-2)
1 solutions

Answer 457368 by tommyt3rd(545) About Me  on 2013-05-22 19:21:22 (Show Source):
You can put this solution on YOUR website!
I assume you mean to solve for d...

5(d+4)=7(d-2)

5d+20=7d-14


5d-5d+20+14=7d-5d-14+14


34=2d

d=17


:)


Trigonometry-basics/750962: how to find the value of sin 1380 cos 225 and tan 420
1 solutions

Answer 457366 by lwsshak3(6505) About Me  on 2013-05-22 19:05:06 (Show Source):
You can put this solution on YOUR website!
how to find the value of sin 1380 cos 225 and tan 420
***
1380-3*360=1380-1080=300
sin(1380)=sin(300)=sin(60)=-√3/2 (in Q4 where sin<0)
..
cos(225)=cos(45)=-√2/2 (in Q3 where cos<0)
..
420-360=60
tan(420)=tan(60)=√3 (in Q1 where tan>0)


test/751686:
1 solutions

Answer 457365 by tommyt3rd(545) About Me  on 2013-05-22 18:51:12 (Show Source):
You can put this solution on YOUR website!
please repost to include a question :)


Complex_Numbers/751680: Use the quadratic formula to solve the quadratic equation x^2 − 8x − 4 = 0.

1 solutions

Answer 457364 by tommyt3rd(545) About Me  on 2013-05-22 18:45:47 (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 1x%5E2%2B-8x%2B-4+=+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=%28-8%29%5E2-4%2A1%2A-4=80.

Discriminant d=80 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--8%2B-sqrt%28+80+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-8%29%2Bsqrt%28+80+%29%29%2F2%5C1+=+8.47213595499958
x%5B2%5D+=+%28-%28-8%29-sqrt%28+80+%29%29%2F2%5C1+=+-0.47213595499958

Quadratic expression 1x%5E2%2B-8x%2B-4 can be factored:
1x%5E2%2B-8x%2B-4+=+1%28x-8.47213595499958%29%2A%28x--0.47213595499958%29
Again, the answer is: 8.47213595499958, -0.47213595499958. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+1%2Ax%5E2%2B-8%2Ax%2B-4+%29


Trigonometry-basics/751013: Find the exact value of csc 5pi%2F4.
Some quick help would be greatly appreciated. :)
1 solutions

Answer 457363 by lwsshak3(6505) About Me  on 2013-05-22 18:40:36 (Show Source):
You can put this solution on YOUR website!
Find the exact value of csc 5pi%2F4
sin(5π/4)=-√2/2 (in Q3 where sin<0)
csc(5π/4)=1/sin(5π/4)=-2/√2=-√2


Quadratic_Equations/751687: You are building a rectangular deck. The area of the deck should be 250 ft squared. You want the length of the deck to be 5 ft longer than twice its width. What should the dimensions of the deck be?
Any help is appreciated
1 solutions

Answer 457362 by rothauserc(208) About Me  on 2013-05-22 18:36:29 (Show Source):
You can put this solution on YOUR website!
You are building a rectangular deck. The area of the deck should be 250 ft squared. You want the length of the deck to be 5 ft longer than twice its width.
let w be the width and 2w+5 is the length, then
w(2w+5) = 250
2w^2+5w-250=0
(2w+25) * (w-10) = 0 and
w=10 and l = 25


Trigonometry-basics/751014: Find the exact value of cot 2pi%2F3.
Some quick help would be greatly appreciated. :)
1 solutions

Answer 457361 by lwsshak3(6505) About Me  on 2013-05-22 18:35:16 (Show Source):
You can put this solution on YOUR website!
Find the exact value of cot 2pi%2F3.
tan(2π/3)=-√3 (in Q2 where tan<0)
cot 2π/3=1/tan 2π/3=-1/√3=-√3/3