Question

if x=3-2 root 2 find the value of x^3+1/x^3

Answer 1

Answer:

198

To Find :x^3+1/x^3

Step-by-step explanation:

x=3-2√2

x^3=(3-2√2)^3

=27-16√2-18√2(3-2√2)

=27-16√2-54√2+72

=99-70√2--------------------------------(1)

1/x=1/(3-2√2)

Now rationalising it.......

1/x=3+2√2

1/x^3=(3+2√2)^3

=27+16√2+18√2(3+2√2)

=27+16√2+54√2+72

=99+70√2-----------------------------------(2)

Now adding (1) and (2)

x^3+1/x^3= 99+99+70√2-70√2

=99+99

=198