Question

求值:(3x的平方)的3次方-7x的3次方[x的3次方-x(4x的平方+1)]+(-x的平方)的平方.其中x=2分之1

Answer 1

(3x^2)^3-7x^3[x^3-x(4x^2+1)]+(-x^2)^2

=3x^6-7x^3[x^3-4x^3-x]+x^4

=3x^6+21x^6+7x^4+x^4

=24x^6+8x^4=8x^4(3x^2+1)

=8(1/2)^4[3(1/2)^2+1]=(1/2)(7/4)=7/8