a, \(=15x^2-20x+18x^2-9x-2x^2+10x=31x^2-19x\)
b, \(=2x^2+x-x^3-2x^2+x^3-x+3=2x^2+3\)
c, \(=-\left(5x-8\right)\left(x+2\right)+4\left(x^2-x-2\right)+2\left(x^2-4\right)+10\)
\(=-\left(5x^2+2x-18\right)+4x^2-4x-8+2x^2-8+10=x^2-6x+12\)
a: \(5\left(3x^2-4x\right)+9\left(2x^2-x\right)-2\left(x^2-5x\right)\)
\(=15x^2-20x+18x^2-9x-2x^2+10x\)
\(=31x^2-19x\)
c: \(x\left(2x+1\right)-x^2\left(x+2\right)+\left(x^3-x+3\right)\)
\(=2x^2+x-x^3-2x^2+x^3-x+3\)
=3
b: \(\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)
\(=8x+16-5x^2-10x+4\left(x^2-x-2\right)+2\left(x^2-4\right)+10\)
\(=-5x^2-2x+26+4x^2-4x-8+2x^2-8\)
\(=x^2-6x+10\)
