Elimination method

[teddybear]

Hi
I am having trouble with understanding how to use elimination method
for example 2x+3y=-16 and 5x-10y=30 can anyone tell me sep by step how to do this

 

[wjm11]

I am having trouble with understanding how to use elimination method
for example 2x+3y=-16 and 5x-10y=30 can anyone tell me sep by step how to do this

First line the equations up, one over the other. Also, line the variables up:

2x+3y=-16
5x-10y=30

Suppose we decide to “eliminate” the x variable. The coefficients of x in the two equations are 2 and 5. Therefore, multiply the top equation by 5 and the bottom equation by –2. the reason for the minus sign on the 2 will soon become evident: it guarantees that when we add the equations together, we’ll be adding a positive 10x with a negative 10x:

5(2x+3y) = 5(-16)
(-2)(5x-10y) = (-2)(30) becomes

10x + 15y = -80
-10x + 20y = -60
_______________ add these equations together:
35y = -140

Therefore y = -140/35 = -4
Now plug –4 in for y in one of the equations to solve for x. Then plug both the x and y solution into the other equation as a check.