a, \(=x^3+x^2-1+x^3-2x^2+x^2+x-2=2x^3+x-3\)
c, \(=2x^2+x-3-\left(3x^2+5x-2\right)=2x^2+x-3-3x^2-5x+2\\ =-x^2-4x-1\)
b, \(=x^2-1-\left(x-2\right)\left(x-1\right)-x^2-2x=-1-2x-\left(x^2-3x+2\right)=-1-2x-x^2+3x-2=-x^2+x-3\)
d, \(=3x^2-5x-2+x^2+5x+6-4x^2+20x=20x+4\)
a: \(-x\left(x^2-x+1\right)+\dfrac{1}{2}x^2\left(2x-4\right)+x\left(x+1\right)-2\)
\(=-x^3+x^2-x+x^3-2x^2+x^2+x-2\)
=-2
c: \(\left(2x+3\right)\left(x-1\right)-\left(3x-1\right)\left(x+2\right)\)
\(=2x^2-2x+3x-3-\left(3x^2+6x-x-2\right)\)
\(=2x^2+x-3-3x^2-5x+2\)
\(=-x^2-4x-1\)
b: \(\left(x-1\right)\left(x+1\right)+\left(2-x\right)\left(x-1\right)-x\left(x+2\right)\)
\(=\left(x-1\right)\left(x+1+2-x\right)-x\left(x+2\right)\)
=3(x-1)-x(x+2)
=3x-3-x2-2x
=-x2+x-3
b: \(\left(3x+1\right)\left(x-2\right)+\left(x+2\right)\left(x+3\right)-4x\left(x-5\right)\)
\(=3x^2-6x+x-2+x^2+5x+6-4x^2+20x\)
=20x+4
