Question

Given the system of equations presented here:

4x + y = 4
2x + 7y = 28
Which of the following actions creates an equivalent system such that, when combined with the other equation, one of the variables is eliminated? (5 points)
Multiply the second equation by −1 to get −2x − 7y = −28
Multiply the second equation by −4 to get −8x − 28y = −112
Multiply the first equation by −7 to get −28x − 7y = −28
Multiply the first equation by −2 to get −8x − 2y = −8

Answer 1

Answer: multiply the first equatiom by -7 to get -28x -7y =-28

Explanation:

4x + y = 4 ------------(1)

2x + 7y = 28 -----------(2)

multiply equation (1) by -7

-28x - 7y = -28 ---------(3)

add equation (2) and (3)

-24x = 0

Divide bothside by 24

x =0

substitute x= 0 in equation(1)

4x +y = 4

4(0) + y = 4

y = 4

Answer 2

multiply the first equation by - 7 to get - 28x - 7y = - 28

Explanation:

This then results on adding the 2 equations as

- 24x = 0 ⇒ x = 0 and y = 4

solution to system is (0, 4 )