Question

On my last birthday, a friend said

to me:
"In 15 years' time, your age will be
the square of your age 15 years
ago!"
Can you work out how old I am?

Answer 1

let the present age be x.
(x-15)^2=×+15
=>×^2-31*×+210=0
=> (x-21)(x-10)=0
x=10 or x=21
present age can not be 10 as it would result at absurd negative age (-5) 15 years ago.
so present age is 21.

Answer 2

let thee present age be x.

(x-15)^2=x+15

=>x^2–31*x+210=0

=>(x-21)(x-10)=0

x=10 or x=21

present age can not be 10 as it would result at absurd negative age( -5) 15 years ago.

so present age is 21.