Mathematics

If the lines 2y – kx + 2 = 0 and y + x -…

If the lines 2y – kx + 2 = 0 and y + x – k/2 = 0 Intersect at (1, -2), find the value of k
  • A.
    -4
  • B.
    -3
  • C.
    -2
  • D.
    -1
Correct Answer: Option C
Explanation

If the point of intersection is (1, -2), it implies that x = 1 and y = -2 when the two equation are solved simultaneously.
∴ substitute x = 1 and y = -2 in any of the equations
2y – k x + 2 = 0
2(-2) – k(1) + 2 = 0
-4 – k + 2 = 0
-4 + 2 = k
-2 = k