Eliminating the chosen variable

Question 1

What operation do you use to eliminate y

x + y = 2 (1)

2x - y = 1 (2)

Answer 1

Add equation (1) and (2) to eliminate y

x + 2x = 2 + 1

3x = 3

x = 1

Question 2

What operation do you use to eliminate y

x + y = 2 (1)

2x + y = 3 (2)

Answer 2

Subtract equation (2) by (1) to eliminate y

2x - x = 3 - 2

x = 1

Question 3

What operation do you use to eliminate x

x + y = 2 (1)

2x - y = 1 (2)

Answer 3

Multiply equation (1) by 2 and name it equation (3)

2x + 2y = 4 (3)

Subtract equation (3) by (2) to eliminate x

2y - (-y) = 4 - 1

3y = 3

y = 1

Question 4

What operation do you use to eliminate x

x + y = 2 (1)

2x + 3y = 5 (2)

Answer 4

Multiply equation (1) by 2 and name it equation (3)

2x + 2y = 4 (3)

Subtract equation (2) by (3) to eliminate x

3y - 2y = 5 - 4

y = 1

Question 5

What operation do you use to eliminate x

3x + 5y = 8 (1)

2x + 3y = 5 (2)

Answer 5

Multiply equation (1) by 2 and name it equation (3)

6x + 10y = 16 (3)

Multiply equation (2) by 3 and name it equation (4)

6x + 9y = 15 (4)

Subtract equation (3) by (4) to eliminate x

10y - 9y = 16 - 15

y = 1

Question 6

What operation do you use to eliminate y

3x + 2y = 5 (1)

5x - 4y = 1 (2)

Answer 6

Multiply equation (1) by 2 and name it equation (3)

6x + 4y = 10 (3)

Add equation (2) to (3) to eliminate y

5x + 6x = 1 + 10

11x = 11

x = 1

Question 7

What operation do you use to eliminate y

3x + 5y = 8 (1)

2x + 3y = 5 (2)

Answer 7

Multiply equation (1) by 2 and name it equation (3)

9x + 15y = 24 (3)

Multiply equation (2) by 3 and name it equation (4)

10x + 15y = 25 (4)

Subtract equation (4) by (3) to eliminate y

10x - 9x = 25 - 24

y = 1