A straight line y = mx meets the curve y = x2 – 12x + 40 in two distinct points. If one of them is (5, 5) find the other
-
A.
(5, 6) -
B.
(8, 8) -
C.
(8, 5) -
D.
(7,7) -
E.
(7, 5)
Correct Answer: Option E
Explanation
When y = 5, y = x2 – 12x + 40, becomes
x2 – 12x + 40 = 5
x2 – 12x + 40 – 5 = 0
x2 + 12x + 35 = 0
x2 – 7x – 5x + 35 = 0
x(x – 7) – 5(x – 7) = 0
= (x – 5)(x – 7)
x = 5 or 7