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a ) \(\left(2x-3\right)^3-x\left(2x-1\right)^2\)
\(=\left(2x\right)^3-3.\left(2x\right)^2.3+3.2x.3^2-3^3-x.\left(2x\right)^2-2.2x.1+1^2\)
\(=8x^3-3.4x^2.3+3.2x.9-27-x.4x^2-2.2x.x+1\)
\(=8x^3-36x^2+54x-27-4x^3-4x^2+1\)
\(=4x^3-40x^2+54x-26\)
a ) (2x−3)^3−x(2x−1)^2
=(2x)^3−3.(2x)^2.3+3.2x.3^2−33^−x.(2x)^2−2.2x.1+1^2
=8x^3−3.4x^2.3+3.2x.9−27−x.4x^2−2.2x.x+1
=8x^3−36x^2+54x−27−4x^3−4x2+1
=4x^3−40x^2+54x−26
1)a)3(2x-1)(3x-1)-(2x-3)(9x-1)=0
<=>18x2-15x+1-18x2+29x-3=0
<=>14x-2=0
<=>14x=2
<=>x=1/7
b)4(x+1)2+(2x-1)2-8(x-1)(x+1)=11
<=>4x2+8x+4+4x2-4x+1-8x2+8=11
<=>4x+13=11
<=>4x=11-13
<=>4x=-2
<=>x=-1/2
c)Sai đề phải là dấu - chứ không phải +
(x-3)(x2+3x+9)-x(x-2)(x+2)=1
<=>x3-27-x3+4x=1
<=>4x=1+27
<=>4x=28
<=>x=7
2)a)(2x-3y)(2x+3y)-4(x-y)2-8xy
=4x2-9y2-4x2+8xy-4y2-8xy
=-13y2
b)(x-2)3-x(x+1)(x-1)+6x(x-3)
=x3-6x2+12x+8-x3+x+6x2-18x
=8-5x
c)(x-2)(x2-2x+4)(x+2)(x2+2x+4)
=(x-2)(x2+2x+4)(x+2)(x2-2x+4)
=(x3-8)(x3+8)
=x6-64
a) (2x+1)^2+2(4x^2-2)+(2x-1)^2=4x2+4x+1+8x2-4+4x2-4x+1=16x2-2
\(A=2x^3+3\left(x-1\right)\left(x+1\right)-5x\left(x+1\right)\)
\(=2x^3+3\left(x^2-1\right)-5x^2-5x\)
\(=2x^3+3x^2-3-5x^2-5x\)
\(=2x^3-2x^2-5x-3\)
\(B=\left(5-2x\right)^3-\left(3x+5\right)\left(5-3x\right)\)
\(=125-150x+60x^2-8x^3-\left(25-9x^2\right)\)
\(=125-150x+60x^2-8x^3-25+9x^2\)
\(=100-15x+69x^2-8x^3\)
\(C=\left(3x+1\right)^2-\left(2x-1\right)^2\)
\(=\left(3x+1-2x+1\right)\left(3x+1+2x-1\right)\)
\(=\left(x+2\right).5x\)
\(D=\left(2x+1\right)^2+\left(3-x\right)^2-2\left(2x+1\right)\left(3-x\right)\)
\(=\left(2x+1-3+x\right)^2\)
\(=\left(3x-2\right)^2\)
\(E=\left(x-2\right)^3-x\left(x+1\right)\left(x-1\right)+6x\left(x-3\right)\)
\(=x^3-6x^2+12x-8+x\left(x^2-1\right)+6x^2-18x\)
\(=x^3-6x^2+12x-8+x^3-x+6x^2-18x\)
\(=-7x-8\)
\(F=\left(x-1\right)^3-3\left(1-x\right)\left(x+1\right)-\left(x^2+x+1\right)\left(x-1\right)-3x\)
\(=x^3-3x^2+3x-1-3\left(1-x^2\right)-\left(x^3-1\right)-3x\)
\(=x^3-3x^2+3x-1-3+3x^2-x^3+1-3x\)
\(=-3\)
a) Ta có: \(\left(x+1\right)\left(x^2-x+1\right)-\left(x-1\right)\left(x^2+x+1\right)\)
\(=x^3+1-x^3+1\)
=2
b) Ta có: \(\left(2x+3\right)\left(2x-3\right)-\left(2x+1\right)^2\)
\(=4x^2-9-4x^2-4x-1\)
\(=-4x-10\)