Question

product of pragati 's age 2 year ago and 3 year hence is 84 . find her present number ​

Answer 1

Let her present age be x.

Therefore her age 2 years ago was (x-2) and after 3 years will be (x+3).

(x-2)(x+3)=84

X*2 +3x - 2x - 6=84

X*2 + x - 6-84=0

X*2 +x - 90=0

NOW FACTORISE

X*2 +10x-9x - 90=0

x(x+10) - 9 (x+10)=0

(x+10)(x-9)=0

X=9 or X=-10

Since age cannot be negative, therefore rejecting x=-10, we get x=9 and hence present age of pragati is 9 years.