23 tháng 1 lúc 19:45
a: \(\left(x-1\right)\left(2x^2-3x+1\right)\)
\(=2x^3-3x^2+x-2x^2+3x-1\)
\(=2x^3-5x^2+4x-1\)
b: \(\left(2+x\right)\left(-x^2+3x-1\right)\)
\(=-2x^2+6x-2-x^3+3x^2-x\)
\(=-x^3+x^2+5x-2\)
c: \(\left(-0,4x-\dfrac{1}{5}x^2\right)\left(-\dfrac{5}{2}x^4-10x^3+6\right)\)
\(=x^5+4x^4-2,4x+\dfrac{1}{2}x^6+2x^5-\dfrac{6}{5}x^2\)
\(=\dfrac{1}{2}x^6+3x^5+4x^4-\dfrac{6}{5}x^2-2,4x\)
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