SOLUTION: Find the choice below which gives a first step in solving the given system of equations by the addition method. 2x -3 y= 7 X-4y = 2 Do you; multiply the first equation by 3 a

Algebra ->  Equations -> SOLUTION: Find the choice below which gives a first step in solving the given system of equations by the addition method. 2x -3 y= 7 X-4y = 2 Do you; multiply the first equation by 3 a      Log On


   



Question 614535: Find the choice below which gives a first step in solving the given system of equations by the addition method.
2x -3 y= 7
X-4y = 2
Do you; multiply the first equation by 3 and the second by 4
- multiply the first equation by -4 and the second by -2
-Multiply the second equation by 2
- Multiply the first equation by 4

Answer by sophxmai(62) About Me  (Show Source):
You can put this solution on YOUR website!
2x-3y=7
x-4y=2

The first step is to multiply the 2nd equation by 2.
This is because in order to solve it, you must cancel out one of the variables.
By multiplying the 2nd equation by 2, you can subtract the new equation (from multiplying the 2nd equation by 2) from the 1st equation, and get 0x. This leaves you with only y. You can then solve for y, and then plug y back into an equation with x and find x.

2x-3y=7
x-4y=2

Multiply the 2nd equation by 2
(x-4y=2)x2
2x-8y=4

Subtract this from the first equation
2x-3y=7
2x-8y=4
-------
5y=3

Solve for y
5y=3
y=3%2F5

Plug y back into an equation with x
x-4y=2
x-4%283%2F5%29=2
x-12%2F5=2
x=2%2B12%2F5
x=22%2F5