Question

x的平方减3x加1等于0,求x的四次方减7x的平方加1等于几?

Answer 1

x^2-3x+1=0

x^2=3x-1

x^4=(3x-1)^2=9x^2-6x+1

x^4-7x^2+1=9x^2-6x+1-7x^2+1

=2x^2-6x+2

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

=0