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