Question

A girl's age in 12 years' time is the square
of her present age. Find her present age.

Answer 1

Answer: her present age is 4

Explanation:

Proof: 4+12=16

Square root 4 is 16

Answer 2

4

Explanation:

Let x represent her present age. The given relation is ...

x +12 = x^2

Putting this in standard form, we can factor it:

x^2 -x -12 = 0

(x -4)(x +3) = 0

Solutions to this quadratic are x = 4, x = -3. The -3 solution is extraneous in this context.

The girl's present age is 4.