Question

An equivalent equation has been written by multiplying the second equation by 2.

4x – 9y = 7 → 4x – 9y = 7
2(–2x + 3y = 4) → –4x + 6y = 8

What is the solution to the system?

a: (-19/2, -5)
b: (-5, -19/2)
c: (-15/2, -11/3)
d: -19/10, 1/15)

Answer 1

(-19/2, -5)

Explanation:

Given the two equivalent equations

4x – 9y = 7 .... 1

–4x + 6y = 8 ....2

Adding both equations

-9y + 6y = 7+8

-3y = 15

y = -15/3

y = -5

Substitute y = -5 into 1

From 1; 4x - 9y = 7

4x - 9(-5) = 7

4x + 45 = 7

4x = 7 - 45

4x = -38

x = -38/4

x = -19/2

Hence the solution is (-19/2, -5)