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24 tháng 7 2016

\(\left(+\right)A=\left(2x+3\right)\left(4x^2-6x+9\right)-2\left(4x^3-1\right).\)

\(A=8x^3-6x^2-18x+27-8x^3+2\)

\(A=6x^2-18x+29\)

\(\left(+\right)B=\left(x-1\right)^3-\left(x+1\right)^3+6\left(x-1\right)\left(x+1\right)\)

\(B=x^3-3x^2+3x+1-x^3-3x^2-3x-1+6\left(x^2-1\right)\)

\(B=-6x^2+6x^2-6\)

\(B=-6\)

21 tháng 7 2021

a/ 2x\(^{^{ }3}\)-3\(^{^{ }3}\)-2x\(^3\)-1\(^{^{ }3}\)=-28

b/x\(^{^{ }3}\)+2\(^{^{ }3}\)-x\(^3\)+2=10

c/3x\(^3\)+5\(^3\)-3x(3x\(^2\)-1)=3x\(^3\)+5\(^3\)-3x\(^3\)+3x=125+3x

d/ x\(^6\)-(x\(^3\)+1)(x\(^2\)-x+1)= x\(^6\)-(x\(^6\)-x\(^4\)+x\(^3\)+x\(^2\)-x+1)=x\(^4\)-x\(^3\)-x\(^2\)+x-1

21 tháng 10 2015

câu c (x+3)(x^2-3x+9)-(54+x^3)=x^3+27-54-x^3

=27

7 tháng 12 2019

d) \(\frac{4x^2-12x+9}{9-4x^2}=-\frac{\left(2x+3\right)^2}{\left(2x-3\right)\left(2x+3\right)}=\frac{2x+3}{2x-3}\)

1 tháng 8 2021

A = \(\left(3x-1\right)^2+2\left(3x-1\right)\left(2x+1\right)+\left(2x+1\right)^2\)

A = \(\left(3x-1+2x+1\right)^2\)

 

1 tháng 8 2021

A)

<=>(3x)^2−2×3x+1+2(3x−1)(2x+1)+(2x+1)^2

<=>(3x)^2−2×3x+1+(6x−2)(2x+1)+(2x+1)^2

<=>(3x)^2−2×3x+1+12x^2+6x−4x−2+(2x+1)^2

<=>(3x)^2−2×3x+1+12x^2+6x−4x−2+(2x)^2+2×2x+1

<=>32x^2−2×3x+1+12x^2+6x−4x−2+(2x)^2+2×2x+1

<=>9x^2−2×3x+1+12x^2+6x−4x−2+(2x)^2+2×2x+1

<=>9x^2−2×3x+1+12x^2+6x−4x−2+2^2x^2+2×2x+1

<=>9x^2−2×3x+1+12x^2+6x−4x−2+4x^2+2×2x+1

<=>9x^2−6x+1+12x^2+6x−4x−2+4x^2+2×2x+1

<=>9x^2−6x+1+12x^2+6x−4x−2+4x^2+4x+1

<=>(9x^2+12x^2+4x^2)+(−6x+6x−4x+4x)+(1−2+1)

<=> 25x^2

B)

<=>2x(4x^2−6x+9)+3(4x^2−6x+9)+8(1−x)(1+x+x^2)

<=>8x^3−12x^2+18x+3(4x^2−6x+9)+8(1−x)(1+x+x^2)

<=>8x^3−12x^2+18x+12x^2−18x+27+8(1−x)(1+x+x^2)

<=>8x^3−12x^2+18x+12x^2−18x+27+(8−8x)(1+x+x^2)

<=>8x^3−12x^2+18x+12x^2−18x+27+8(1+x+x^2)−8x(1+x+x^2)

<=>8x^3−12x^2+18x+12x^2−18x+27+8+8x+8x^2−8x(1+x+x^2)

<=>8x^3−12x^2+18x+12x^2−18x+27+8+8x+8x^2−(8x+8x2+8x^3)

<=>8x^3−12x^2+18x+12x^2−18x+27+8+8x+8x^2−8x−8x^2−8x^3

<=>(8x^3−8x^3)+(−12x^2+12x^2+8x^2−8x^2)+(18x−18x+8x−8x)+(27+8)

<=> 35

 

27 tháng 9 2021

\(B=\left(2x-3\right)\left(4x^2+6x+9\right)-\left(x+1\right)^2-\left(x-2\right)^3\)

\(=8x^3-27-x^2-2x-1-x^3+6x^2-12x+8\)

\(=7x^3+5x^2-14x-20\)