Bài 3:
a: A=(3x+7)(2x+3)-(3x-5)(2x+11)
\(=6x^2+9x+14x+21-6x^2-33x+10x+55=76\)
b: \(\left(x^2-2\right)\left(x^2+x-1\right)-x\left(x^3+x^2-3x-2\right)\)
\(=x^4+x^3-x^2-2x^2-2x+2-x^4-x^3+3x^2+2x=2\)
c: x(x^3+x^2-3x-2)-(x^2-2)(x^2+x-1)
=-2
d: =2x^2+x-x^3-2x^2+x^3-x+3
=3
e: =x^3+1-x^3+1
=2
f: =8x^3+27-8x^3+2
=29