SOLUTION: WHAT DOES IT MEAN BY SUBTITUTION WITH THIS PROBLEM 3X-5Y=-12 X+ 2Y=7

Question 21231: WHAT DOES IT MEAN BY SUBTITUTION WITH THIS PROBLEM
3X-5Y=-12
X+ 2Y=7
Answer by elima(1433) (Show Source): You can put this solution on YOUR website!
3X-5Y=-12
X+ 2Y=7
It just means you will solve one equation for x or y, and substitute that answer in the other equation to solve. Lets start by find x, so we will take the secind equation and solve for x;
x+2y=7
subtract 2y from both sides;
x+2y-2y=7-2y
x=7-2y
Now we have what x = so we can substitute it in the other equation so we can solve for y;
3(7-2y)-5y=-12
distribute the 3;
21-6y-5y=-12
21-11y=-12
subtract 21 from both sides;
21-11y=-12-21
-11y=-33
Divide each side by -11;
=
y=3
Now we now what y =, so now solve the equation for x, lets use the second equation only becuase it is easier;
x+2y=7
x+2(3)=7
x+6=7
x=1
It doesn't matter which equation you start with, you should just use the easier one to solve.
Hope you understand
=)
RELATED QUESTIONS
solve by subtitution: 1/5x + 1/2y = 8 x +y = 20 solve by subtitution: 6x + 5y = -3 (answered by checkley77)

Im getting stuck on this system of equation by subtitution: Exercise 1 x=3y+7 (answered by rfer)

SOLVE THE SYSTEM BY ADDING OR SUBTITUTION 3X+6y=0 x=2/3 solve the sysem by adding... (answered by malakumar_kos@yahoo.com)

Im getting stuck on this system of equation by subtitution: Exercise xy=-12... (answered by Alan3354,josgarithmetic)

Solve the following system of equation by subtitution or elemination (x+8)/7=(3-5y)/4... (answered by Fombitz)

X=5Y 5X-25Y=5 I WOULD LIKE TO KNOW HOW TO SLOVE THIS PROBLEM IT IS SUBTITUTION OF... (answered by checkley71)

When using the subtitution maethod: 3x+y=7 2x-5y= -1 7-3x=y so, 2x-... (answered by jim_thompson5910)

This problem asks me to factor by grouping. Problem: 5xy+25x-2y-10 What does it mean by (answered by nerdybill)

I am having problems with these equations by subtitution. 8y=15-4x x+2y=4 (answered by josmiceli,Earlsdon)