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\(a,\frac{1}{64}x^6-125y^3\)
\(=\left(\frac{1}{2}x\right)^6-\left(5y\right)^3\)
\(=\left(\frac{1}{4}x^2\right)^3-\left(5y\right)^3\)
\(\left(\frac{1}{4}x^2-5y\right)\left[\left(\frac{1}{4}x^2\right)^2+\left(\frac{1}{4}x^2\right).5y+25y^2\right]\)
\(b,27a^3-54a^2b+36ab^2-8b^3\)
\(=\left(3a\right)^3-3.2.\left(3a\right)^2b+3.3a.\left(2b\right)^2-\left(2b\right)^3\)
\(=\left(3a-2b\right)^3\)
\(c,x^6-x^6\)
\(=0\)
\(d,10x-25-x^2\)
\(=-x^2+10x-25\)
\(=-\left(x^2-10x+25\right)\)
\(=-\left(x-5\right)^2\)
a: \(\left(2x^2+3y\right)^3\)
\(=8x^6+3\cdot4x^4\cdot3y+3\cdot2x^2\cdot9y^2+27y^3\)
\(=8x^6+36x^4y+54x^2y^2+27y^3\)
b: \(\left(2a^2b+\dfrac{1}{3}ab^2\right)^2\)
\(=4a^4b^2+2\cdot2a^2b\cdot\dfrac{1}{3}ab^2+\dfrac{1}{9}a^2b^4\)
\(=4a^4b^2+\dfrac{4}{3}a^3b^3+\dfrac{1}{9}a^2b^4\)
Ta có ;
\(0.008-a^3b^6\)
\(=\left(0.2\right)^3-\left(ab^2\right)^3\)
\(=\left(0.2-ab^2\right)\left(0.04+0.2ab^2+a^2b^4\right)\)
\(0,008=0,2^3,a^6b^3=\left(a^2b\right)^3\)
=> \(0,2^3-\left(a^2b\right)^3=\left(0,2-a^2b\right)\left(0,04+0,2ab+a^4b^2\right)\)
\(4x^2-20xy^2+25y^4=\left(2x\right)^2-2.2x.5y^2+\left(5y^2\right)^2=\left(2x-5y^2\right)^2\)
Áp dụng hằng đẳng thức: \(\left(A-B\right)^2=A^2-2AB+B^2\)
\(4x^2-20xy^2+25y^4\)
\(=\left(2x\right)^2-2\cdot2x\cdot5y^2+\left(5y\right)^2\)
\(=\left(2x-5y\right)^2\)
Ta có :
\(\left(3x^2+2y\right)\left(2y-3x^2\right)\)
\(=\left(2y+3x^2\right)\left(2y-3x^2\right)\)
\(=\left(2y\right)^2-\left(3x^2\right)^2\)
\(=4y^2-9x^4\)
\(\frac{1}{4}x^6-0,01y^2=\left(\frac{1}{2}x^3\right)^2-\left(0,1y\right)^2\)
\(=\left(\frac{1}{2}x^3-0,1y\right).\left(\frac{1}{2}x^3+0,1y\right)\)
Vậy \(\frac{1}{4}x^6-0,01y^2\)\(=\left(\frac{1}{2}x^3-0,1y\right).\left(\frac{1}{2}x^3+0,1y\right)\)
Tham khảo nhé ~
\(\frac{1}{4}x^6-0.01y^2\)
\(=\left(\frac{1}{2}x^3\right)^2-\left(0.1y\right)^2\)
\(=\left(\frac{1}{2}x^3-0.1y\right)\left(\frac{1}{2}x^3+0.1y\right)\)
Mong lần này không sai nữa ......
\(27a^3-b^3+9ab^2-27a^2b\)
\(=\left(3a\right)^3-3\cdot\left(3a\right)^2b+3\cdot3a\cdot b^2-b^3\)
\(=\left(3a-b\right)^3\)