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Integration of dx/(x^2+1)^3 2016-01-07
From Ishank:
Integration of dx/(x^2+1)^3
Answered by Penny Nom.
A linear system 2014-10-14
From pheter:
4/x - 1/y = 3 .... equation (1)
6/x - 2/y = 5 .... equation (2)

Answered by Penny Nom.
Evaluate x-(3x+5) if x=-2 2014-04-03
From Destiny:
I wanted to know the value of x-(3x+5) if x=-2
Answered by Penny Nom.
f(x)= a+b*lnx 2013-12-04
From Kevin:
How do I find the curve, algebraically on paper, for f(x)= a+b*lnx with data points (6,1303) (9,1639). I can do it with LnReg on a calculator but I want to know how to get the same results or close to the same results by working it out on paper. When I run it through the LnReg on the calculator I get, f(x)=181.792+828.678 Ln x. How did it achieve this solution?
Answered by Penny Nom.
Substitution type simultaneous equations 2013-11-03
From Kayla:
I am having problems with substitution type simultaneous equations, when the variable you are substituting is a algebraic one:
y=x^2-3x+4 and 3x-2y=1
I have rearranged 3x-2y=1 to get x=(1+2y)/3 but when I substitute this x value into the other equation, I get the wrong answers!
Would appreciate any help! Thank you.

Answered by Penny Nom.
Integral 1/(25-x^2)^3/2 2012-02-22
From John:
Integral 1/(25-x^2)^3/2
Answered by Harley Weston.
Elimination and substitution 2010-09-18
From Lauren:
Solve one using the method of substitution and the other with the method of elimination.

v a. y=5x+4

b. 4x+3y=7

Answered by Penny Nom.
y = kx 2010-03-26
From harold:
if y =kx and y =4/15 and x=2/3, what is value of k
Answered by Penny Nom.
The integral of X^3/the square root of 1-x^2 dx 2010-03-07
From William:
The integral of X^3/the square root of 1-x^2 dx.
Answered by Harley Weston.
Substitution method 2010-02-17
From Melodie:
7x - 4y = -10
4y= x-2

Answered by Tyler Wood.
Substitution 2010-02-14
From Izayah:
what is 3 ways to find the meeting point of y=2x+4 and 3x+y=7 by making 2 table and using a graph
Answered by Stephen La Rocque.
An integral 2010-01-29
From amr:
find the value of the following integral:- (1+x)power (-1/2) dx
Answered by Robert Dawson.
The method of substitution 2009-09-17
From laura:
ok! i really need help with this question plz help!!

x= - 4y +5
x+2y = 7

Answered by Penny Nom.
Substitution in a quadratic 2009-03-09
From Kieran:
How could I work this out please

f(x)= 3xsquared - 4x + 2

if f(2x)

Answered by Penny Nom.
Linear systems 2009-02-20
From Rose:
I have been having trouble trying to figure out these three math problems , I need help breaking them down so I could understand them better please help.
1. x = 7 - x
2 x - y + 8

2. 8 x + 5 y = 1 8 4
x - y = 3

3. y + 2 x = 3
y + 2 x = 4

I can't figure out how to break them down in the right order.

Answered by Penny Nom.
The substitution method 2009-02-18
From Nicolette:
I am working on linear programming problems that I need to solve pairs of linear equations for. I am confused and am not sure how to solve these problems!
5x+3y=7      y=x-3 How can i solve this using the substitution method?

Answered by Penny Nom.
A definite integral 2009-02-09
From Mathata:
Evaluate: integral from 0 to 1, x^2 e^x^3dx
Answered by Harley Weston.
The substitution method 2009-02-06
From amber:
Pleasse help me with this problem

Answered by Penny Nom.
The integral of f(x)dx and the integral of f(x-4)dx 2009-01-02
From Katie:
Calculus: If the definite integral from -2 to 6 of f(x)dx=10 and the definite integral from 2 to 6 of f(x)dx=3, then the definite integral from 2 to 6 of f(x-4)dx= ?

I don't understand how to solve definite integrals when the function has something more than just x inside the parenthesis such as f(4-x).

Answered by Robert Dawson.
The substitution method 2008-07-26
From Enid:
Solve by substitution method
3x + 7y = 25
-7x + y = 63

Answered by Penny Nom.
A rectangular room 2008-06-30
From Peter:
A rectangular room has a perimeter of 42 feet and an area of 108 square feet. What is the length, in feet, of the shorter side?
Answered by Penny Nom.
Substitution into a formula 2008-06-02
From beth:
Given q(x) = 7xsquared + 9, find q(-7)

These were the choices I had for the answers to this problem
1.) 343
2.) -40
3.) 334
4.) -89
5.) 352

Answered by Penny Nom.
Substitution method 2008-05-30
From taquicia:

Answered by Janice Cotcher.
Integrate 2x(x^2-1)^5 dx 2008-04-17
From joey:
pls help me to integrate
2x(x^2-1)^5 dx using the substitution u=x^2-1

Answered by Harley Weston.
The integral of dx / (4x^2 - 25)^3/2 2008-04-01
From Meghan:
I have a question from the trigonometric substitution of my calculus course.

integral of dx / (4x^2 - 25)^3/2

Answered by Harley Weston.
An integral 2008-01-24
From Meghan:
Evaluate the indefinite integral of (x^3 +1)^(1/3) * x^5 * dx.
Answered by Brennan Yaremko.
Substitution method 2007-10-11
From Kevin:
Answered by Stephen La Rocque.
Two equations in two unknowns 2007-09-22
From Mary:
Having problems doing this problem, looking for a solution with the work. I would like to see how you got your answer, to see what I was doing wrong.

solve using the substitution method, is there "no solution" or "infinitely many solutions"


Answered by Stephen La Rocque and Leeanne Boehm.
Solve by substitution 2007-07-28
From Marina:
I am stuck with this substition please help. -3x+y=1 5x+2y=-4
Answered by Penny Nom.
The substitution method 2007-06-23
From mary:
solve the system by the method of substitution: -5x+2y=-15 4x-y=9
Answered by Stephen La Rocque.
The substitution method 2007-05-08
From A student:
I need help on these two problems( substitution method)

x-3y= -3
6x-8y= -12

Answered by Penny Nom.
Solve for x and y 2007-03-27
From anthony:
solve y=4x and x+y=5
Answered by Sara Ulmer.
Simultaneous equations with fractions 2007-02-28
From Alyca:
Hello Math Central, I am a grade 10 student taking Academic math. Our unit right now is method of substitution and elimination. I'm stuck on this one question that I've been doing forever. Please help =)

*For this equation I have to do method of elimination, but it's so much harder with fractions...could some one please explain to me how to do it step by step?*
x y 2
-- - -- = - --
3 6 3

x y 1
-- - -- = 1---
12 4 2

Answered by Steve La Rocque and Ashley Mang.
The substitution method 2007-01-31
From Victoria:
how do i solve this problem using the substitution method?
2x-5= -14
-7x+14y= -5

Answered by Stephen La Rocque.
The substitution method 2005-06-28
From Addie:
how do i know where to began the substitution method? how do i solve y = x + 1 2x - y = 1
Answered by Penny Nom.
The substitution method 2004-11-28
From A student:
I Was working and i ran into this problem can you help me solve it using the substitution method?


Answered by Penny Nom.
The method of substitution 2004-09-20
From Kayla:

Answered by Harley Weston.
x^2/3 - 7 x^1/3 + 12 = 0 2004-04-05
From Jackie:
I am having trouble solving this question for x:

1.) x^2/3 - 7 x^1/3 + 12 = 0

Answered by Penny Nom.
The substitution method 2004-02-14
From Keisha:
I need to solve this problem by using the substitution method.
Please help me understand the method to solve.

Answered by Penny Nom.
Systems of equations 2003-11-19
From Scott:

I hope that u can help me....I am a college student taking a class in Pre Calculus.....I have homework due this Friday and it counts a BIG Percentage on my FINAL grade.....I am getting mixed up and can not figure out a few problems.....Please help me.....

Method Of Subsitution

Problem 1. y- 8x = -5
x(squared) + y(squared) = 25

Problem 2. y = x(squared) - 2x - 6
Y = x(squared) - 4

Answered by Penny Nom.

5x - y 2003-10-11
From Candace:
math problem 5x-y for x=12 and y=14 do you mulitilpy 5x12 and than -the answer from 14 which gives you 46? is this right
Answered by Penny Nom.
Substitution method 2003-09-14
From John:

Hello, my name is john and while I was finishing up my work I stumbled into these problems. a/4-b=-1

Thanks a lot. I really need some help :)

Answered by Penny Nom.
Two equations 2003-08-21
From Jennifer:

The following problems have me stuck and any help would be greatly appreciated seeing my text book is doing me no favours:

32a+1 - 283a + 9=0
52m - 5m=20

Answered by Penny Nom.
The substitution method 2003-04-14
From Patty:

I need help with the following:

5x - 4y = 13

2y + 3x = -1

Answered by Penny Nom.
The substitution method 2002-11-15
From A student:
Solve by using the substitution method.

x = 3y - 1
x + 2y = 9

Answered by Penny Nom.
Substitution 2002-11-06
From John Paul:
I took a math test last week, and there was a problem which the teacher checked as incorrect. It was:

Solve: (a)RcTc=360;(b)RmTm=480;(c)Rm=2Rc; (d)Tm+Tc=15

I solved the problem and I got the following values for each variable.

For Rc=40 For Tc=9
For Rm=96 For Tm=5

I don't see nothing wrong, but the teacher checked it as wrong. Could it be a checking mistake?

Answered by Claude Tardif.
18m-11+ -7 2002-11-06
From Sophia:
what is 18m-11+ -7 (m = to 12)?
Answered by Penny Nom.
Algebra 2002-09-08
From Heather:
This question is from an 8th grade Algebra classs. I am a parent asking for help to explain to my child. Q: d=25t2.
Answered by Leeanne Boehm.
x + 5 + x, if x = 4 2002-07-23
From Elisa:
x + 5 + x, if x = 4
Answered by Leeanne Boehm.
The substitution method 2002-02-24
From Joe:
whats the answer to this question? 3x+y=11

its substitution method i am having alot of trouble figuring it out. send the answer as soon as possible. thank you

Answered by Penny Nom.
The substitution method 2001-03-05
From A student:
Solve each system of equations by the substitution method. Show your work.
  1. y = 8
    7x = 1 - y

  2. y = x - 1
    4x - y = 19

Answered by Penny Nom.
Some integration problems 2000-02-23
From Tim Valentine:
I am having a great deal of difficulty with the following integrals, can you help? I think they need the use of trig substitution or integration by parts but I cannot figure out how to begin. Thanks!

The integral of 1/(2+3x2) dx.


The integral of x * square root of (4x+5) dx.

Answered by Harley Weston.
Algebre 2009-03-04
From Jonnathan:
Pour entrer sur le site d'une exposition, il en coute 41$ pour 2 enfants et 2 adultes mais 37.50$ pour 3 enfants et un adulte. Quel est le prix de la rentree pour l'enfant et quel est le prix de la rentree pour l'adulte? il faut utiliser la methode de comparaison ou de substitution
Answered by Claude Tardif.



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