Question

Please use elimination method to solve

Answer 1

(4, - 1 )

Explanation:

2x + 7y = 1 → (1)

3x + 4y = 8 → (2)

multiplying (1) by 3 and (2) by - 2 and adding will eliminate x

6x + 21y = 3 → (3)

- 6x - 8y = - 16 → (4)

add (3) and (4) term by term to eliminate x

0 + 13y = - 13

13y = - 13 ( divide both sides by 13 )

y = - 1

substitute y = - 1 into either of the 2 equations and solve for x

substituting into (1)

2x + 7(- 1) = 1

2x - 7 = 1 ( add 7 to both sides )

2x = 8 ( divide both sides by 2 )

x = 4

solution is (4, - 1 )

Answer 2

The answer is x = 4, y = -1 or (4, -1).

We are given :

1. 2x + 7y = 1
2. 3x + 4y = 8

Multiply the 1st equation with 3 and 2nd equation with 2.

3. 3(2x + 7y) = 3(1) ⇒ 6x + 21y = 3

4. 2(3x + 4y) = 2(8) ⇒ 6x + 8y = 16

Now, subtract : Equation 3 - Equation 4.

• 6x + 21y - 6x - 8y = 3 - 16
• 13y = -13
• y = -1

Substitute in the 1st equation.

• 3x + 4(-1) = 8
• 3x - 4 = 8
• 3x = 12
• x = 4