Find the solution of the equation x – 8(sqrt{x}) + 15 = 0
-
A.
3, 5 -
B.
-3, -5 -
C.
9, 25 -
D.
-9, 25
Correct Answer: Option C
Explanation
x – 8(sqrt{x}) + 15 = 0
x + 15 = 8(sqrt{x})
square both sides = (x + 15)2 = (8 (sqrt{x})2
x2 + 225 + 30x = 64x
x2 + 225 + 30x – 64x = 0
x2 – 34x + 225 = 0
(x – 9)(x – 25) = 0
x = 9 or 25