Question

Solve 15x+3y=9,10x+7y=-4

Answer 1

x = 1, y = -2

Explanation:

15x + 3y = 9 (1)

10x + 7y = -4 (2)

3 × (2) - 2 × (1)

3 × (2)

30x + 21y = -12 (3)

2 × (1)

30x + 6y = 18 (4)

(3) - (4)

15y = -30

y = -30 / 15

y = -2

sub y = -2 into (1)

15x + 3y = 9

15x + (3 × -2) = 9

15x - 6 = 9

15x = 9 + 6

15x = 15

x = 15 / 15

x = 1