Question

If x^2 -x-1=0 ,find x^3 - 2x+1 ....

Answer 1

x^2 - x -1 =0.....................(1)
x^3 - 2x+1 = x^3 - 2x+1 ;
                  =[ x +1]x  -2x + 1{(1)  x^2 = x +1}
                  = x^2 +x  -2x +1
                 =  [x^2 -x - 1 ]+ 1 + 1
                 = [0] +2
                  =2//

Answer 2

Answer:2

Step-by-step explanation:x^2=x+1

x^3-2x+1=x(x^2)-2x+1

= x(x+1)-2x+1

=x^2+x-2x+1

=(x+1)-x+1

=x+1-x+1

=2