已知2x^2-3=0,求代数式x^2(x^2-1)^2+x^2(5-x^2)^2-9的值

问题描述:

已知2x^2-3=0,求代数式x^2(x^2-1)^2+x^2(5-x^2)^2-9的值

2x^2-3=0→x^2=3/2
代数式x^2(x^2-1)^2+x^2(5-x^2)^2-9
=3/2(3/2-1)^2+3/2(5-3/2)^2-9
=3/2(1/2)^2+3/2(7/2)^2-9
=3/2(1/4+49/4)-9
=3/2×25/2-9
=75/4-9
=39/4