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17 tháng 11 2018

\(\left(x-1\right)^2-25\)

\(=x^2-2x+1-25\)

\(=x^2-2x-24\)

\(=x^2-6x+4x-24\)

\(=x.\left(x-6\right)+4.\left(x-6\right)\)

\(=\left(x+4\right).\left(x-6\right)\)

17 tháng 11 2018

a, \(1-2y+y^2=\left(y+1\right)^2=\left(y+1\right)\left(y+1\right)\)

b, \(\left(x+1\right)^2-25=\left(x+1\right)^2-5^2=\left(x+1-5\right)\left(x+1+5\right)=\left(x-4\right)\left(x+6\right)\)

c, \(1-4x^2=1^2-\left(2x\right)^2=\left(1-2x\right)\left(1+2x\right)\)

d,  \(8-27x^3=2^3-\left(3x\right)^3=\left(2-3x\right)\left(4+6x+9x^2\right)\)

3 tháng 7 2018

a) \(A=8x^3+12x^2y+6xy^2+y^3=\left(2x+y\right)^3\)

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

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

d)  \(D=27+27y^2+9y^4+y^6=\left(3+y^2\right)^3\)

21 tháng 6 2018

giúp mình vs ạbucminh

a) Ta có: \(x^2+2x+1\)

\(=x^2+2\cdot x\cdot1+1^2\)

\(=\left(x+1\right)^2\)

b) Ta có: \(1-2y+y^2\)

\(=y^2-2\cdot y\cdot1+1^2\)

\(=\left(y-1\right)^2\)

c) Ta có: \(x^3-3x^2+3x-1\)

\(=x^3-x^2-2x^2+2x+x-1\)

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

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

\(=\left(x-1\right)^3\)

d) Ta có: \(27+27x+9x^2+x^3\)

\(=x^3+3x^2+6x^2+18x+9x+27\)

\(=x^2\left(x+3\right)+6x\left(x+3\right)+9\left(x+3\right)\)

\(=\left(x+3\right)\left(x^2+6x+9\right)\)

\(=\left(x+3\right)^3\)

e) Ta có: \(8-125x^3\)

\(=2^3-\left(5x\right)^3\)

\(=\left(2-5x\right)\left(4+10x+25x^2\right)\)

f) Ta có: \(64x^3+\frac{1}{8}\)

\(=\left(4x\right)^3+\left(\frac{1}{2}\right)^3\)

\(=\left(4x+\frac{1}{2}\right)\left(16x^2-2x+\frac{1}{4}\right)\)

g) Ta có: \(1-x^2y^4\)

\(=1^2-\left(xy^2\right)^2\)

\(=\left(1-xy^2\right)\left(1+xy^2\right)\)

16 tháng 8 2020

a) \(x^2+2x+1=x^2+2x.1+1^2=\left(x+1\right)^2\)

b) \(1-2y+y^2=1^2-2y.1+y^2=\left(1-y\right)^2\)

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

d) \(27+27x+9x^2+x^3=3^3+3.3^2x+3.3x^2+x^3=\left(3+x\right)^3\)

e) \(8-125x^3=2^3-\left(5x\right)^3=\left(2-5x\right)\left[2^2+2.5x+\left(5x\right)^2\right]=\left(2-5x\right)\left(4+10x+25x^2\right)\)

f) \(64x^3+\frac{1}{8}=\left(4x\right)^3+\left(\frac{1}{2}\right)^3=\left(4x+\frac{1}{2}\right)\left[\left(4x\right)^2-4x.\frac{1}{2}+\left(\frac{1}{2}\right)^2\right]=\left(4x+\frac{1}{2}\right)\left(16x^2-2x+\frac{1}{4}\right)\)

Ko chắc ạ!