Question

the product of ages of a student before 4 years and after 8 years is 28 find his present age

Answer 1

let the present age of student = x years
A.T.Q
(x-4)(x+8)=28
x2+8x-4x-32=28
x2+4x=28+32
x2+4x=60
x2+4x-60=0
x2+10x-6x-60=0
x(x+10)-6(x+10)=0
(x-6)(x+10)=0
either x-6=0
x=6

or x+10=0
x=-10

so, age is 6 years because age is not negative..

Answer 2

Let the present age of student be x.

By the given condition,

(x-4)(x+8)=28
x^2+4x-32=28
x^2+4x-32-28=0

x^2+4x-60=0
x^2+10x-6x-60=0
x(x+10)-6(x+10)=0
(x+10)(x-6)=0
x+10=0 OR x-6=0
x=-10 OR x=6

But x = -10 is not acceptable

so,

x=6.

Therefore,
the students present age is 6yrs.


Hope this helps!!!