JAMB - Mathematics (2007 - No. 39)
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
-1
Объяснение
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
∴ 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