Question

4 solve the following simultaneous equations using elimination method:

(iii) 2x - y = 2, 5x + y = -9

Answer 1

(- 1, - 4 )

Explanation:

Given the 2 equations

2x - y = 2 → (1)

5x + y = - 9 → (2)

Adding the 2 equations term by term will eliminate the y- term, that is

7x + 0 = - 7

7x = - 7 ( divide both sides by 7 )

x = - 1

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

Substituting into (2)

5(- 1) + y = - 9

- 5 + y = - 9 ( add 5 to both sides )

y = - 4

solution is (- 1, - 4 )

Answer 2

Explanation:

As instructed

Use Elimination Method....

2x - y = 2

2x - 2 = y

y = 2x - 2 ----------- equation 1

5x + y = -9

Substitute for y

5x + 2x - 2 = -9

7x = -9 + 2

7x = -7

x = -7/7

x = -1

Substitute for x in equation 1

y = 2x - 2

y = 2(-1) - 2

y = -2 - 2

y = -4