Mathematics

If x – 3 is directly proportional to the square of y and x =…

If x – 3 is directly proportional to the square of y and x = 5 when y =2, find x when y = 6.
  • A.
    30
  • B.
    21
  • C.
    16
  • D.
    12
Correct Answer: Option B
Explanation

(x – 3) ∝ y2
X-3 = Ky2
K = X-3 / y2
= 5-2/22
= 2/4
= 1/2
∴X-3 = 1/2y2
X-3 = 1/2(6)2
X-3 = 1/2 x 30/1
X-3 = 18
X = 21