Sonia is x years old now.
Her age in 12 years' time is the square of her
present age.
(a) Form an equation in x and show that it
reduces to x-x-12 = 0.
(b) Hence find her present age.
Her age now ---- x
her age 12 years from now --- x + 12
x^2 = x+12
x^2 - x - 12 = 0
a) does not reduce to the equation you quoted
b) (x-4)(x+3) = 0 , where x > 0
x = 4
her present age is 4
check:
in 12 years she will be 16, which is the 4^2, the square of her present age.