Question

thực hiện phép tính :

a)2x^2+3(x-1)(x+1)-5x(x+1)

b) (8-5x)(x+2)+4(x-2)(x+1)+2(x-2)(x+2)+10

c) 4(x-1)(x+5)-(x+2)(x+5)-3(x-1)(x+2)

Answer 1

a)\(2x^2+3\left(x-1\right)\left(x+1\right)-5x\left(x+1\right)\)

\(=2x^2+3x^2-3-5x^2-5x\)

\(=-3-5x\).

b)\(\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)

\(=8x+16-5x^2-10x+4x^2-4x-8+2x^2-8+10\)

\(=3x^2-6x+10\).

Answer 2

c)\(4\left(x+1\right)\left(x+5\right)-\left(x+2\right)\left(x+5\right)-3\left(x+1\right)\left(x+2\right)\)

=\(4x^2+20x-4x-20-x^2-5x-2x-10-3x^2-6x+3x+6\)

\(=6x-30\).

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