Multiple choice

Find the present age of a boy whose age $12$ years from now will be the square of his present age.

  1. $5\ years$
  2. $7\ years$
  3. $4\ years$
  4. $6\ years$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let age be x. x + 12 = x^2. x^2 - x - 12 = 0. (x - 4)(x + 3) = 0. Since age must be positive, x = 4.

AI explanation

Let the boy's present age be x years. In 12 years, his age will be x + 12, which is stated to be the square of his present age, giving the equation x squared equals x + 12. Rearranging this yields x squared minus x minus 12 equals 0. Factoring this gives (x minus 4)(x plus 3) equals 0, so the positive value for his present age is x equals 4 years.

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