Question

已知x=1/x,求（x²-5/x-1+1）乘以x³-1/x²-2x除以（x+3）的值

Answer 1

x=1/x则x=±1

（x²-5/x-1+1）乘以x³-1/x²-2x除以（x+3）

=(x²-5/x)X(x³-1/x²-2x)÷(x+3)

=[(x^3-5)/x]X[(x^5-1-2x^3)/x^2]÷(x+3)

=(x^3-5)(x^5-2x^3-1)/[x^3(x+3)]

当x=1时

=(1-5)(1-2-1)/(1+3)

=(-4)(-2)/4

=2

当x=-1时

=(-1-5)(-1+2-1)/(-1)(-1+3)

=(-4)(0)/(-2)

=0