Question

2x+y=1 9x + 3y = -3 The x-coordinate of the point of intersection is :

A. 5
B. -2
C. 0

Answer 1

B

given the 2 equations

2x + y = 1 → (1)

9x + 3y = - 3 → (2)

from (1) : y = 1 - 2x

substitute y = 1 - 2x in (2)

9x + 3(1 - 2x) = - 3 ( distribute and simplify left side )

9x + 3 - 6x = - 3

3x + 3 = - 3 ( subtract 3 from both sides )

3x = - 6 ( divide both sides by 3 )

x = - 2 → B