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A = (x - 1)3 - x(x - 2)2 + 1
A = (x - 1)(x2 - 2x + 1) - x(x - 2)2 + 1
A = x(x2 - 2x + 1) - (x2 - 2x + 1) - x(x - 2)2 + 1
A = x3 - 2x2 + x - (x2 - 2x + 1) - x(x2 - 2x.2 + 22) + 1
A = x3 - 2x2 + x - (x2 - 2x + 1) - (x3 - 4x2 + 4x) + 1
A = x3 - 2x2 + x - x2 + 2x - 1 - x3 + 4x2 - 4x + 1
A = (x3 - x3) + (-2x2 - x2 + 4x2) + (x + 2x - 4x) + (-1 + 1)
A = x2 - x
B = (-x - 2)3 + (2x - 4)(x2 + 2x + 4) - x2(x - 6)
B = (-x - 2)[(-x2) - 2.(-x).2 + 22] + (2x - 4)(x2 + 2x + 4) - x2(x - 6)
B = -x[(-x)2 - 2.(-x).2 + 22] - 2[(-x)2 - 2.(-x).2 + 22] + (2x - 4)(x2 + 2x + 4) - x2(x - 6)
B = -(x3 + 4x2 + 4x) - (2x2 + 4x + 8) + 2x(x2 + 2x + 4) - 4(x2 + 2x + 4) - x2(x - 6)
B = -(x3 + 4x2 - 4x) - (2x2 + 4x + 8) + 2x3 + 4x2 + 8x - (x2 + 8x + 16) - (x3 - 6x2)
B = -x3 - 4x2 + 4x - 2x2 - 4x - 8 + 2x3 + 4x2 + 8x - x2 - 8x - 16 - x3 + 6x2
B = (-x3 + 2x3 - x3) + (-4x2 - 2x2 + 4x2 - x2 + 6x2) + (-4x - 8x + 8x - 8x) + (-8 - 16)
B = -12x - 24
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a.ta có
\(\left(x+3\right)^3+\left(x^2+1\right)\left(x-2\right)=x^3+9x^2+27x+27+x^3-2x^2+x-2\)
\(=2x^3+7x^2+28x+25\)
b.\(\left(2x-1\right)^2-\left(2-x\right)^3=4x^2-4x+1+x^3-6x^2+12x-8\)
\(=x^3-2x^2+8x-7\)
a) (x + 3)3 + (x2 + 1)(x - 2)
= x3 + 9x2 + 27x + 27 + x3 - 2x + x - 2
= x3 + x3 + 9x2 + 27x - 2x + x + 27 - 2
= 2x3 + 9x2 + 26x + 25
b) (2x - 1)2 - (2 - x)3
= 4x2 - 4x + 1 - ( 8 - 12x + 6x2 - x3)
= 4x2 - 4x + 1 - 8 + 12x - 6x2 + x3
= x3 + 4x2 - 6x2 + 12x - 4x + 1 - 8
= x3 - 2x2 + 8x - 7
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`Answer:`
`a)`
`A=5(x+1)^2-3(x-3)^2-4(x^2-4)`
`=>A=5(x^2+2x+1)-3(x^2-6x+9)-4x^2+16`
`=>A=5x^2+10x+5-3x^2+18x-27-4x^2+16`
`=>A=(5x^2-3x^2-4x^2)+(10x+18x)+(5-27+16)`
`=>A=-2x^2+28x-6`
`b)`
`B=5(x+1)^2-3(x-3)^2-4(x+2)(x-2)`
`=2x(3x+5)-3(3x+5)-2x(x^2-4x+4)-[(2x)^2-3^2]`
`=6x^2+10x-9x-15-2x^3+8x^2-8x-4x^2+9`
`=(6x^2-4x^2+8x^2)-2x^3+(10x-9x-8x)+(-15+9)`
Thay `x=-7` vào ta được:
`B=10(-7)^2-2(-7)^3-7(-7)-6`
`=>B=10.49-2(-343)+49-6`
`=>B=490+686+49-6`
`=>B=1219`
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a: =18x^3y^2-12x^3y^3+6x^2y^2
b: (-3x+2)(5x^2-1/3x+4)
=-12x^3+x^2-12x+10x^2-2/3x+8
=-12x^3+11x^2-38/3x+8
c: =x^2-x-2+3x-x^2
=2x-2
d: =4x^2+12x+9-4x^2+25-(x-1)(x^2+12)
=12x+34-x^3-12x+x^2+12
=-x^3+x^2+46
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a) x(x + 1) - 2x(x - 2) = x2 + x - 2x2 + 4x = -x2 + 5x
b) -3x(x - 1) + (x - 1)(x + 1) = -3x2 + 3x + x2 - 1 = -2x2 + 3x - 1
c) (3x - 2)(3x + 2) - (x - 1)(x + 2) = 9x2 - 4 - x2 - x + 2
= 8x2 - x - 2
a, x(x+1) - 2x(x -2 )
= x2 +x - 2x2 + 4x = -x2 + 5x
b, -3x( x - 1 ) + ( x -1 ) ( x+1 )
= -3x2 + 3x + x2 -1
= -2x2 + 3x -1
c, ( 3x-2 ) ( 3x + 2 ) - ( x -1 ) ( x +2 )
= 9x2 - 4 - ( x2 + 2x -x -2 )
= 9x2 -4 - x2 -2x + x + 2
= 8x2 -x -2
*Sxl
\(\text{ 2x.(x-2)+(x+3).(1-2x)}\\ =\left(2x^2-4x\right)+\left(x-2x^2+3-6x\right)\\ =2x\left(x-2\right)+\left(-5-2x^2+3\right)\)