Question

Which statement correctly explains how Dana can solve the following system of linear equations for x using the elimination method?

4x+8y=20
-4x+2y= -30
Add the two equations, solve for y, and then substitute –1 for y to find x.
Multiply the bottom equation by –4, solve for y, and then substitute –1 for y to find x.
Multiply the bottom equation by –1, combine the two equations, solve for y, and then substitute 1 for y to find x.
Multiply the two equations, solve for y, and then substitute 1 for y to find x.

Answer 1

A

Explanation:

3dg 2020 answer

Answer 2

1. The correct statement is the first one, which is: Add the two equations, solve for y, and then substitute –1 for y to find x.

2. Therefore, you have the following system of equations:

4x+8y=20
-4x+2y= -30

3. When you add the two equations, and clear the variable "y", you obtain:

10y=-10
y=-1

4. Now, you must substitute -1 for y (y=-1) to find x, as below:

4x+8y=20
4x+8(-1)=20
4x-8=20
4x=20+8
4x=28
x=28/4
x=7