Question

The product of ages of a student before 4 years and after 8 years is 28. Find his present age

Answer 1

let, present age be x years
as per the problem
(x-4)(x+8)=28
x^2+8x-4x-32=28
x^2+4x-60=0
x^2+10x-6x-60=0
x(x+10)-6(x+10)=0
(x-6)(x+10)=0
x=6;x=-10
we know that age is always +ve
therefore ,x =6
hence present age is 6 years

Answer 2

here is your answer
according to question
let the age to be x
(x-4)(x+8)=28          
 as per identity (x+a)(x+b)=x^2+xb-xa-ab
x^2+8x-4x-32=28
x^2+4x-60=0
x^2+10x-6x-60=0
x(x+10)-6(x+10)=0
(x-6)(x+10)=0
x=6;x=-10
age of any person is always +ve
therefore ,x =6
hence present age is 6 years
of student