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lwsshak3 answered: 6492 problems
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Quadratic_Equations/686234: solve the equation using the quadratic formula method:3a^2x^2-abx-2b^2=0

1 solutions

Answer 424722 by lwsshak3(6494) About Me  on 2012-11-28 00:27:25 (Show Source):
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solve the equation using the quadratic formula method:3a^2x^2-abx-2b^2=0
use following quadratic formula to solve:
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a=3a^2, b=-ab, c=-2b^2
I will let you take it from here


Rational-functions/686232: Please help rationalize the problem below with brief step-by-step explanation. Thank you in advance for your time and assistance!
(2)/(3t)^(1/2)
1 solutions

Answer 424721 by lwsshak3(6494) About Me  on 2012-11-28 00:19:38 (Show Source):
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(2)/(3t)^(1/2)
(2)/√(3t)
multiply top and bottom by √(3t)
(2)/√(3t)*√(3t)/√(3t)
2√(3t)/3t


test/686223: Find the value of k so that the three points lie on the same line. Write the equation in point slope form. The points given are (1,-2) (-2,4) (4,k)
1 solutions

Answer 424720 by lwsshak3(6494) About Me  on 2012-11-28 00:11:58 (Show Source):
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Find the value of k so that the three points lie on the same line. Write the equation in point slope form. The points given are (1,-2) (-2,4) (4,k)
**
y-y1=m(x-x1)
using given point (1,-2)
y-(-2)=m(x-1)
y+2=m(x-1)
using given points (1,-2) and (-2,4) to find slope,m
m=∆y/∆x=(4-(-2))/(-2-1)=(4+2)/-3=6/-3=-2
y+2=-2(x-1)
y+2=-2x+2
y=-2x
solving for k
k=-2*4=-8
k=-8
see graph below:
+graph%28+300%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C-2x%29+


Travel_Word_Problems/685928: you can travel 40 miles on motorcycle in the same time that it takes to travel 15 miles on bicycle. if your motorcycle's rate is 20 miles per hour faster than your bicycle's, fine the average rate for each
1 solutions

Answer 424657 by lwsshak3(6494) About Me  on 2012-11-27 16:32:22 (Show Source):
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you can travel 40 miles on motorcycle in the same time that it takes to travel 15 miles on bicycle. if your motorcycle's rate is 20 miles per hour faster than your bicycle's, fine the average rate for each
let x=rate of speed of bicycle
x+20=rate of speed of motorcycle
travel time= distance/rate of speed (same for both)
40/(x+20)=15/x
40x=15(x+20
40x=15x+300
25x=300
x=12
x+20=32
rate of speed of bicycle=12 mph
rate of speed of motorcycle=32 mph


Expressions-with-variables/685894: Find an equation of the line passing (-7,2) and (4,5)
1 solutions

Answer 424649 by lwsshak3(6494) About Me  on 2012-11-27 16:19:52 (Show Source):
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Find an equation of the line passing (-7,2) and (4,5)
Equation of a line: y=mx+b, m=slope, b=y-intercept
For given problem:
m=∆y/∆x=(5-2)/(4-(-7))=3/11
equation: y=3x/11+b
solve for b using one of given coordinates(4,5)
5=3*4/11+b
b=5-12/11
b=55/11-12/11=43/11
equation: y=3x/11+43/11
see graph below:
+graph%28+300%2C+300%2C+-10%2C+10%2C+-10%2C+10%2C3x%2F11%2B43%2F11%29+


Quadratic_Equations/685893: Please help me with this question. I'm getting really confused with the 3x. I' not sure where to start.
Find all of the exact solutions to the following equation. (Use the parameter k as necessary to represent any integer.)
cos(3x) =1/2

1 solutions

Answer 424643 by lwsshak3(6494) About Me  on 2012-11-27 16:04:57 (Show Source):
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Find all of the exact solutions to the following equation. (Use the parameter k as necessary to represent any integer.)
cos(3x) =1/2
3x=π/3+2πk, 5π/3+2πk, k=any integer
x=π/9+2πk, 5π/9+2πk, k=any integer


Exponential-and-logarithmic-functions/685808: Solve the following exponential equation. Exact answers only.
49^x-12*7^x=-36
I have tried and tried on this problem. I do not understand. I would appreciate help on this! Thank you!
1 solutions

Answer 424637 by lwsshak3(6494) About Me  on 2012-11-27 15:57:15 (Show Source):
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Solve the following exponential equation. Exact answers only.
49^x-12*7^x=-36
7^2x-12*7^x=-36
let u=7^x
u^2=7^2x
u^2-12u+36=0
(u-6)(u-6)=0
u=6=7^x
6=7^x
log6=xlog7
x=log6/log7
x≈.9208..


Geometry_Word_Problems/685869: In an isosceles triangle, the base is 7 more than one-half times the legs. If perimeter is 22 centimeters. Find length of each leg.
1 solutions

Answer 424619 by lwsshak3(6494) About Me  on 2012-11-27 14:57:23 (Show Source):
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In an isosceles triangle, the base is 7 more than one-half times the legs. If perimeter is 22 centimeters. Find length of each leg.
**
let x=length of each leg
base+2 legs=perimeter
(1/2)x+7+2x=22
x/2+7+2x=22
5x/2=15
5x=30
x=6
length of each leg=6 cm


logarithm/685867: I need help solving this question.
write the following as a single logarithm with coefficient of 1. please show steps. thanks in adavance
3logc(x^4)-2logc(3x)

1 solutions

Answer 424614 by lwsshak3(6494) About Me  on 2012-11-27 14:48:21 (Show Source):
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write the following as a single logarithm with coefficient of 1. please show steps. thanks in adavance
3logc(x^4)-2logc(3x)
logc[(x^4)^3/(3x)^2]
logc[(x^12/(9x^2]
logc[(x^10/9)]


Length-and-distance/685863: Two cars leave towns 640 kilometers apart at the same time and travel toward each other. One car's rate is 10 kilometers per hour more than the other's. If they meet in 4 hours, what is the rate of the faster car?
1 solutions

Answer 424612 by lwsshak3(6494) About Me  on 2012-11-27 14:44:54 (Show Source):
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Two cars leave towns 640 kilometers apart at the same time and travel toward each other. One car's rate is 10 kilometers per hour more than the other's. If they meet in 4 hours, what is the rate of the faster car?
**
let x=rate of speed of faster car
x-10=rate of speed of slower car
distance=rate of speed*travel time
4x+4(x-10)=640
4x+4x-40=640
8x=680
x=85
rate of speed of faster car= 85km/hr


Mixture_Word_Problems/685848: A metal alloy weighing 12 lb. and containing
20% copper is melted and mixed with 3 lb. of a
different alloy which contains 40% copper.
What percent of the resulting alloy is copper?
1 solutions

Answer 424609 by lwsshak3(6494) About Me  on 2012-11-27 14:35:43 (Show Source):
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A metal alloy weighing 12 lb. and containing
20% copper is melted and mixed with 3 lb. of a
different alloy which contains 40% copper.
What percent of the resulting alloy is copper?
**
20%*12+40%*3/12+3=(2.4+1.2)/15=3.6/15=.24
What percent of the resulting alloy is copper? 24%


logarithm/685036: Solve the logarithmic equation algebraically.Approximate the result to three decimal places.
log(4x)-log(14+the square root of x)=2
1 solutions

Answer 424513 by lwsshak3(6494) About Me  on 2012-11-27 02:44:35 (Show Source):
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Solve the logarithmic equation algebraically.Approximate the result to three decimal places.
log(4x)-log(14+the square root of x)=2
**
log(4x)-log(14+√x)=2
log[4x/(14+x^(1/2))=2
convert to exponential form
10^2=4x/(14+x^(1/2))=100
4x=1400+100x^(1/2)
4x-1400-100x^(1/2)=0
let u=x^(1/2)
u^2=x
4u^2-100u-1400=0
u^2-25u-350=0
(u-35)(u+10)
u=35=√x
x=35^2=1225
or
u=-10=√x
x=(-10)^2=100
ans:
x=1225
or
x=100


logarithm/685592: Solve each equation for x
A). ln(2x-3)=-1
B). ln(3x+1)=2

(they are natural)
1 solutions

Answer 424509 by lwsshak3(6494) About Me  on 2012-11-27 02:05:30 (Show Source):
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Solve each equation for x
A). ln(2x-3)=-1
2x-3=e^-1=1/e
2x=1/e+3
x=(1/e+3)/2
x=1.6839
..
B). ln(3x+1)=2
3x+1=e^2
3x=e^2-1
x=(e^2-1)/3
x=2.1297


logarithm/685594: Solve each exponential equation for x. Give an exact solution and also approximate the solution to four decimals
a). 4^(3x+2)=9
b). 5^(3x-5)=4
1 solutions

Answer 424508 by lwsshak3(6494) About Me  on 2012-11-27 01:56:21 (Show Source):
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Solve each exponential equation for x. Give an exact solution and also approximate the solution to four decimals
a). 4^(3x+2)=9
(3x+2)log4=log9
(3x+2)=log9/log4
3x=(log9/log4)-2
x=[(log9/log4)-2]/3 (exact solution)
x=-0.1383..
..
b). 5^(3x-5)=4
(3x-5)log5=log4
3x-5=log4/log5
x=[(log4/log5)+5]/3 (exact solution)
x=1.9538..


logarithm/685595: Find all the real number roots of the equation.
log2(x+7)-log2(x-3)=3
1 solutions

Answer 424507 by lwsshak3(6494) About Me  on 2012-11-27 01:38:20 (Show Source):
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Find all the real number roots of the equation.
log2(x+7)-log2(x-3)=3
log2[(x+7)/(x-3)]=3
convert to exponential form
(x+7)/(x-3)=2^3=8
x+7=8x-24
7x=31
x=31/7=4.4286..


logarithm/685596: log5(x-2)= 2 + log5(x-4)

1 solutions

Answer 424506 by lwsshak3(6494) About Me  on 2012-11-27 01:32:45 (Show Source):
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log5(x-2)= 2 + log5(x-4)
log5(x-2)- log5(x-4)=2
log5[(x-2)/(x-4)]=2
convert to exponential form
(x-2)/(x-4)=5^2=25
x-2=25x-100
24x=98
x=4.0833..


logarithm/685597: Solve each exponential equation for x. Give an exact solution and also approximate the solution to four decimals
2*5^(x-1)=1
1 solutions

Answer 424505 by lwsshak3(6494) About Me  on 2012-11-27 01:19:57 (Show Source):
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Solve each exponential equation for x. Give an exact solution and also approximate the solution to four decimals
2*5^(x-1)=1
log2+(x-1)log5=log1
log1=0
log2+(x-1)log5=0
log2+(x-1)log5=-log2
x-1=-log2/log5
x=(-log2/log5)+1 (exact solution)
x=0.5963..


logarithm/685605: randy invested his inheritance in an account that paid 6.9% interest, coupounded continuously. after 5 years, he found that he now had $52,565.56. what was the orginal amount of his inheritance?

1 solutions

Answer 424504 by lwsshak3(6494) About Me  on 2012-11-27 01:09:00 (Show Source):
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randy invested his inheritance in an account that paid 6.9% interest, coupounded continuously. after 5 years, he found that he now had $52,565.56. what was the orginal amount of his inheritance?
**
Formula for continuous compounding:A= Pe^rt, P=initial investment, r=rate of interest, A=amt after t years
52565.56=Pe^(.069*5)=Pe^.345
P=52565.56/e^.345=37228
orginal amount of his inheritance=$37,228.00..


Quadratic-relations-and-conic-sections/684975: E is the ellipse with foci at (4,-2) and (4,8) and whose major axis has length of 20
Find an equation for the indicated conic section
1 solutions

Answer 424503 by lwsshak3(6494) About Me  on 2012-11-27 00:50:05 (Show Source):
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E is the ellipse with foci at (4,-2) and (4,8) and whose major axis has length of 20
Find an equation for the indicated conic section
**
This is an ellipse with vertical major axis.
Its standard form of equation:%28x-h%29%5E2%2Fb%5E2%2B%28y-k%29%5E2%2Fa%5E2=1, a>b, (h,k)=(x,y) coordinates of center
For given ellipse:
center: (4,3)
given length of vertical major axis=20=2a
a=10
a^2=100
c=5 (distance from center to foci)
c^2=25
c^2=a^2-b^2
b^2=a^2-c^2=100-25=75
Equation of given ellipse:
%28x-4%29%5E2%2F75%2B%28y-3%29%5E2%2F100=1


Trigonometry-basics/685106: Find the exact values of each trigonometric function at 0(theta)=-(7pi/12). For sin cos and tan.
1 solutions

Answer 424398 by lwsshak3(6494) About Me  on 2012-11-26 16:47:50 (Show Source):
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Find the exact values of each trigonometric function at 0(theta)=-(7pi/12). For sin cos and tan.
-(7π/12) is in quadrant III where sin<0, cos<0, tan>0
-(7π/12)=[(-3π/12)+(-4π/12)]=[(-π/4)+(-π/3)]
sin-(7π/12)=sin[(-π/4)+(-π/3)]=[sin(-π/4)cos(-π/3)]+[cos(-π/4)sin(-π/3)]
=[(-√2/2)*(1/2)+√2/2*-√3/2]
=[-√2/4-√6/4]
=(-√2-√6)/4
sin-(7π/12)=-(√2+√6)/4
check with calculator:
sin-(7π/12)=-0.9659..
-(√2+√6)/4=-0.9659..
..
cos-(7π/12)=cos[(-π/4)+(-π/3)]=[cos(-π/4)cos(-π/3)]-[sin(-π/4)sin(-π/3)]
=[(√2/2)*(1/2)]-[-√2/2*-√3/2]
=[√2/4-√6/4]
=(√2-√6)/4
check with calculator:
cos-(7π/12)=-0.2588..
(√2-√6)/4=-0.2588..
..
tan-(7π/12)=tan[(-3π/12)+(-4π/12)]=tan[(-π/4)+(-π/3)]
=[tan(-π/4)+tan(-π/3)]/[1-tan(-π/4)*tan(-π/3)]=[-1+(-√3)]/[1-(-1*(-√3)]
=(-1-√3)/(1-√3)
check with calculator:
tan-(7π/12)=3.732..
(-1-√3)/(1-√3)=3.732..


Trigonometry-basics/685119: Find the six trig functions of -pi
1 solutions

Answer 424390 by lwsshak3(6494) About Me  on 2012-11-26 15:05:29 (Show Source):
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Find the six trig functions of -pi
sin -π=0
cos -π=-1
tan -π=0
csc -π=undefined
sec -π=-1
cot -π=undefined


Trigonometry-basics/685120: Given that sin(3θ)= (1/5) and (π/2)<3θ<π: Find cos(3θ), sin(6θ), and tan (3θ/2)
1 solutions

Answer 424388 by lwsshak3(6494) About Me  on 2012-11-26 14:54:31 (Show Source):
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Given that sin(3θ)= (1/5) and (π/2)<3θ<π: Find cos(3θ), sin(6θ), and tan (3θ/2)
You are working with reference angle 3θ in quadrant II where sin>0, cos<0, and tan<0
sin3θ=opposite side/hypotenuse=1/5
adjacent side=√(5^2-1^2)=√(25-1)=√24
..
cos(3θ)=-√24/5
..
Identity: sin 2s=2sins cos s
sin(6θ)=2sin3θcos3θ
=2*1/5*-√24/5
=-(2√24)/25
..
Identity: tan s/2= (sin s)/(1+cos s)
tan (3θ/2)=sin3θ/1+cos3θ
=(1/5)/(1-√24/5)
=(1/5)/(5-√24)/5
=1/(5-√24)


Trigonometry-basics/685127: Solve each equation on the interval (0,2pi): a.) 2sin^(2)x-cos x-1=0, b.) sin 3x cos 2x + cos3x sin2x= (√2/2).
1 solutions

Answer 424381 by lwsshak3(6494) About Me  on 2012-11-26 14:22:31 (Show Source):
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Solve each equation on the interval (0,2pi): a.) 2sin^(2)x-cos x-1=0, b.) sin 3x cos 2x + cos3x sin2x= (√2/2).
**
a.) 2sin^(2)x-cosx-1=0
2(1-cos^2x)-cosx-1=0
2-2cos^2x-cosx-1=0
2cos^2x+cosx-1=0
(2cosx-1)(cosx+1)=0
2cosx-1=0
cosx=1/2
x=π/3, 5π/3
or
cosx+1=0
cosx=-1
x=π
..
b.) sin 3x cos 2x + cos3x sin2x= (√2/2).
Identity:sin(s+t)=sin s cos t+cos s sin t
sin 3x cos 2x + cos3x sin2x= (√2/2)
sin(3x+2x)=sin(5x)=√2/2
5x=π/4, 3π/4
x=π/20, 3π/20


logarithm/683960: Solve for t
10^(7t) = 18^(2t-5)
1 solutions

Answer 423996 by lwsshak3(6494) About Me  on 2012-11-24 03:21:06 (Show Source):
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Solve for t
10^(7t) = 18^(2t-5)
7tlog10=(2t-5)log18
7t/2t-5=log18/log10≈1.2553
7t=1.2553(2t-5)=2.5105t-6.2764
7t-2.5105t=-6.2764
4.4894t=-6.2764
t≈-6.2764/4.4894
t≈-1.3980


logarithm/684125: How would I find the inverse of f(x)=log 9 (x)? Does having the parenthesis around x change it?
Here is what I did:1) re-write it as y=log 9 (x); 2) identify 9 as the base, y as the exponent, and keeping x on the right side of the equation; 3) re-write it as 9^y=x.
1 solutions

Answer 423995 by lwsshak3(6494) About Me  on 2012-11-24 03:01:25 (Show Source):
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The inverse of the log function is the exponential form:
For given problem:y=log 9 (x)
Exponential form: base(9) raised to log of number(y)=number(x)
9^y=x
so, you were right on.


logarithm/684196: Can you help me solve. I'm having problems using the laws. thanks in advance.
Log2t^3-Logt = Log16+Logt

1 solutions

Answer 423994 by lwsshak3(6494) About Me  on 2012-11-24 02:53:43 (Show Source):
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Log2t^3-Logt = Log16+Logt
log[2t^3/t]=log[16/t]
2t^3/t=16/t
2t^3=16
t^3=8
t=2


logarithm/684219: Please help me solve this:
Write as a single logarithm:
1/3[logsubscript4x-logsubscript4y] + 2logsubscript4(3x-4)

1 solutions

Answer 423992 by lwsshak3(6494) About Me  on 2012-11-24 02:48:13 (Show Source):
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Write as a single logarithm:
1/3[logsubscript4x-logsubscript4y] + 2logsubscript4(3x-4)
1/3[log4(x)-log4(y)]+2log4(3x-4)
log4[(x/y)^(1/3)*(3x-4)^2]


Trigonometry-basics/683726: Write the expression as the sine, cosine, or tangent of an angle.
sin 48° cos 15° - cos 48° sin 15°
And also:
Find all solutions to the equation.
cos x = sin x
And:
Verify the identity.
4 csc 2x = 2 csc2x tan x

1 solutions

Answer 423991 by lwsshak3(6494) About Me  on 2012-11-24 02:34:42 (Show Source):
You can put this solution on YOUR website!
Write the expression as the sine, cosine, or tangent of an angle.
sin 48° cos 15° - cos 48° sin 15°
Identity: sin(s-t)=sin s cos t-cos s sin t
sin 48° cos 15° - cos 48° sin 15°=sin(48º-15º)=sin 33º
..
And also:
Find all solutions to the equation.
cos x = sin x
tan x=cos x/sin x=1
x=45º+360ºk, x=225º+360ºk, k=integer
..
And:
Verify the identity.
4 csc(2x) = 2 csc^2x tan x
start with right side
2csc^2x tanx
=2/sin^2x*sinx/cosx
=2/sinx cosx
multiply top and bottom by 2
=4/2sinx cosx
=4/sin(2x)
=4csc(2x)
verified: right side=left side


Travel_Word_Problems/683843: A man drove 156 km at a constant rate. If he had driven 5km/hr. faster he would made the trip in 12 minutes less time. How fast did he drive?
ans. 60 KPH
help me with solution pls..
1 solutions

Answer 423769 by lwsshak3(6494) About Me  on 2012-11-22 02:35:22 (Show Source):
You can put this solution on YOUR website!
A man drove 156 km at a constant rate. If he had driven 5km/hr. faster he would made the trip in 12 minutes less time. How fast did he drive?
ans. 60 KPH
**
let x=how fast he drove
x+5=speed in 12 min less time
156/x-156/(x+5)=12 min=12/60 hr=0.2 hr
156/x-156/(x+5)=.2
LCD: x(x+5)
156(x+5)+156x=x(x+5)(.2)
156x+780+156x=.2x^2+x
.2x^2+x-780=0
2x+10x-7800=0
x+5x-3900=0
(x+65)(x-60)=0
x+65=0
x=-65(reject, x>0)
or
x-60=0
x=60
how fast he drove=60 km/hr


logarithm/683608: log(2x)=1.7
Solve for x
1 solutions

Answer 423767 by lwsshak3(6494) About Me  on 2012-11-22 01:44:59 (Show Source):
You can put this solution on YOUR website!
log(2x)=1.7
Solve for x
2x=10^1.7
x=(10^1.7)/2
x≈25.0594


logarithm/683829: 2. Solve the following exponential equation. Exact answers only.
49^x-12*7^x=-36
1 solutions

Answer 423766 by lwsshak3(6494) About Me  on 2012-11-22 01:37:41 (Show Source):
You can put this solution on YOUR website!
2. Solve the following exponential equation. Exact answers only.
49^x-12*7^x=-36
7^2x-12*7^x+36=0
let u=7^x
u^2=7^2x
u^2-12u+36=0
(u-6)(u-6)=0
u=6=7^x
xlog7=log6
x=log6/log7