Question

Could someone explain to me how to solve this

? I got (-1,2) and it said I was wrong.

never mind found out why, i was supposed to plug in x for one of the equations to find y!

Answer 1

The ordered pair is (–1, –2)

Solution:

Given system of linear equations are

4x –7y = 10 – – – – (1)

3x + 2y = –7 – – – – (2)

To solve this by elimination method.

First multiply equation (1) by 3 and then multiply equation (2) by 4.

(1) × 3 ⇒ 12x –21y = 30 – – – – (3)

(2) × 4 ⇒ 12x + 8y = –28 – – – – (4)

Subtract equation (4) from equation (3), we get

⇒ 12x –21y – (12x + 8y) = 30 – (–28)

⇒ 12x –21y – 12x – 8y = 30 + 28

Combine like terms together.

⇒ 12x – 12x –21y – 8y = 30 + 28

⇒ –29y = 58

Divide both sides by –29, we get

⇒ y = –2

Substitute y = –2 in equation (1), we get

(1) ⇒ 4x –7y = 10

⇒ 4x – 7(–2) = 10

⇒ 4x + 14 = 10

⇒ 4x = 10 – 14

⇒ 4x = –4

Divide both side by 4, we get

⇒ x = –1

Hence the ordered pair for the given system of equations is (–1, –2).