Question

If x = 1/(2-√3), find the value of x³- 2x² - 7x + 5​

Answer 1

Answer:

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