Will give brainliest. to all answerers.

3

Step-by-step explanation:

x= 1/ (2-√3),

Rationalising denominator,

x= 1/(2-√3) *(2+√3)/(2+√3)

x= (2+√3) /22 -(√3)2  = (2+√3) /4-3= (2+√3)

Substituting value of x =(2+√3) in

x3 -2x2 -7x +5, we get

(2+√3)3  -2(2+√3)2 -7(2+√3) +5

= 8 +12√3+18+3√3- 8-8√3-6-14-7√3+5

=3

answer: 8 years

step-by-step explanation:

the explanation is that in 8 years the child will be 20 and in 8 years the father will be 40 and 20 is half of 40.