Đáp án + Giải thích các bước giải:
`a, x(5x^3 -x+1/2)-2x`
`=5x^4 - x^2 + 1/2x - 2x = 5x^4 - x^2 -3/2x`
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`b, (2x-2)(1+2x)+x(5-4x)-x`
`=2x+4x^2-2-4x+5x-4x^2-x = (4x^2-4x^2)+(2x-4x+5x-x)-2=2x-2`
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`c, 4x(4-3x)-(3x+2)(1-4x)`
`=16x-12x^2-(3x-12x^2+2-8x)=16x-2x^2+12x^2+5x-2=21x-2`
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`d, (1-x)(1+x)+(x-3)^2`
`<=> 1^2-x^2 + x^2+6x+9=6x+9+1=6x+10`
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`e, 10x^2 -2x(4x-1)+(2x+5)^2`
`=10x^2 -8x^2+2x+4x^2+2.2x.5+5^2`
`=2x^2+2x+4x^2+20x+25=6x^2+22x+25`
