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

Mathematics JAMB 2007

If the lines 2y – kx + 2 = 0 and y + x – k/2 = 0 Intersect at (1, -2), find the value of k

  • -4
  • -3
  • -2 checkmark
  • -1

The correct answer is: 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
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