Question

If x=3+2√2 , find the value of x- +1/x-

Answer 1

Answer:

Given x=3-2√2

x+1/x=3-2√2+1/(3-2√2)

⇒3-2√2+1/(3-2√2)×(3+2√2)/(3+2√2)

⇒3-2√2+(3+2√2)/[(3)²-(2√2)²]

⇒3-2√2+(3+2√2)/(9-8)

⇒3-2√2+(3+2√2)/1

⇒3-2√2+3+2√2

⇒6.

∴x+1/x=6