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Find the solution of the equation x – 8(sqrt{x}) + 15 = 0

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