Câu 1:
a) \(2x^2\left(-x^2-3x\right)+6x^3\)
\(=-2x^4-6x^3+6x^3\)
\(=-2x^4\)
b) \(-5x.\left(1+x\right)+3x\)
\(=-5x-5x^2+3x\)
\(=-2x-5x^2\)
c) \(-5x^2-2x^2.\left(x-\dfrac{5}{2}\right)\)
\(=-5x^2-2x^3+5x^2\)
\(=-2x^3\)
d) \(2x^2\left(x-1\right)-5\left(x+2\right)-2x\left(x-2\right)\)
\(=2x^3-2x^2-5x-10-2x^2+4x\)
\(=2x^3-2x^2-x-10\)
e) \(x^2\left(2x-3\right)-x\left(x+1\right)-\left(3x-2\right)\)
\(=2x^3-3x^2-x^2-x-3x+2\)
\(=2x^3-4x^2-4x+2\)
2:
a: \(=2x^3-3x^2+x-2x^2+3x-1=2x^3-5x^2+4x-1\)
b: \(=-2x^2+6x-2-x^3+3x^2-x\)
=-x^3+x^2+5x-2
c: \(=x^5+4x^4-2.4x+\dfrac{1}{2}x^6+2x^5-\dfrac{6}{5}x^2\)
\(=\dfrac{1}{2}x^6+3x^5+4x^4-\dfrac{6}{5}x^2-2.4x\)
e: \(=-6x^3+2x^2+18x^2-6x+6x^3-18x^2+18x-2x^2+6x-6\)
\(=-6\)
e: \(=-5x^2+25x+x^3-7x-3x^2+21=xX^3-8x^2+18x+21\)
