\(a.25^2-4a^2+12ab-9b^2\\ =25^2-\left(4a^2+12ab-9b^2\right)\\ =25^2-\left(2a-3b\right)^2\\ =\left(25-2a+3b\right)\left(25+2a-3b\right)\\ b.x^3+x^2y-xy^2-y^3\\ =x^2\left(x+y\right)-y^2\left(x+y\right)\\ =\left(x+y\right)\left(x^2-y^2\right)\\ =\left(x+y\right)\left(x+y\right)\left(x-y\right)\\ =\left(x+y\right)^2\left(x-y\right)\)

a: Ta có: \(25x^2-4a^2+12ab-9b^2\)

\(=25x^2-\left(2a-3b\right)^2\)

\(=\left(5x-2a+3b\right)\left(5x+2a-3b\right)\)

b: Ta có: \(x^3+x^2y-xy^2-y^3\)

\(=\left(x-y\right)\left(x^2+xy+y^2\right)+xy\left(x-y\right)\)

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

4a²b² + 36a²b³ + 6ab⁴

= 2ab²(2a + 18ab + 3b²)

4a²b³ - 6a³b²

= 2a²b²(2b - 3a)

4a²b² + 36a²b³ + 6ab⁴

= 2ab²(2a + 18ab + 3b²)

3n(m - 3) + 5m(m - 3)

= (3n + 5m)(m - 3)

2a(x - y) - (y - x)

= (x - y)(2a + 1)

4a²b³ - 6a³b²

= 2a²b²(2b - 3a)

\(2ab^2-a^2b-b^3=b^2\left(2a-a^2-b\right)\)

\(2ab^2-a^2b-b^3\)

\(=-b\left(a^2-2ab+b^2\right)\)

\(=-b\left(a-b\right)^2\)

-(2ab² - a²b - b³)

= b(-2ab + a² + b²)

= b(a² - 2ab + b²)

= b(a - b)²

\(a,=x^2-9-x^2+6x-9=6x-18\\ b,=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)=\left(x+y-5\right)\left(x-y\right)\)

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

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

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

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

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\(a^3+3a^2-6a-8\)

\(=a^3+4a^2-a^2-4a-2a-8\)

\(=\left(a^3+4a^2\right)-\left(a^2+4a\right)-\left(2a+8\right)\)

\(=a^2\left(a+4\right)-a\left(a+4\right)-2\left(a+4\right)\)

\(=\left(a+4\right)\left(a^2-a-2\right)\)

\(=\left(a+4\right)\left(a^2-2a+a-2\right)\)

\(=\left(a+4\right)\left[\left(a^2-2a\right)+\left(a-2\right)\right]\)

\(=\left(a+4\right)\left[a\left(a-2\right)+\left(a-2\right)\right]\)

\(=\left(a+4\right)\left(a-2\right)\left(a+1\right)\)

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\(2x^2-5x+2\)

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

\(=\left(2x^2-4x\right)-\left(x-2\right)\)

\(=2x\left(x-2\right)-\left(x-2\right)\)

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

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\(x^2-2x-4y^2-4y\)

\(=\left(x^2-4y^2\right)-\left(2x-4y\right)\)

\(=\left(x-2y\right)\left(x+2y\right)-2\left(x-2y\right)\)

\(=\left(x-2y\right)\left(x+2y-2\right)\)

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\(a^2-1+4b-4b^2\)

\(=a^2-\left(1-4b+4b^2\right)\)

\(=a^2-\left(1-2b\right)^2\)

\(=\left(a-1+2b\right)\left(a+1-2b\right)\)

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\(a^4+6a^2b+9b^2-1\)

\(=\left(a^4+6a^2b+9b^2\right)-1\)

\(=\left(a^2+3b\right)^2-1\)

\(=\left(a^2+3b-1\right)\left(a^2+3b+1\right)\)

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\(2x^3+16y^3\)

\(=2\left(x^3+8y^3\right)\)

\(=2\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)

Lần sau ghi đề tách riêng từng câu ra nhé em. Ghi dính chùm vậy khó nhìn lắm. Sẽ ít ai giải cho em

x⁹ + 1
= (x³)³ + 1³
= (x³ + 1)(x⁶ - x³ + 1)
= (x + 1)(x² - x + 1)(x⁶ - x³ +1)

8a³ - 12a² + 6a - 1
= (2a)³ - 3(2a)²1 + 3 . 2a . 1² - 1
= (2a - 1)³

27a³ - 54a²b + 36ab² - 8b³
= (3a)³ - 3(3a)²2b + 3 . 3a . (2b)² - (2b)³
= (3a - 2b)³

Bài 4: 

Ta có: \(\left(x^3-x^2\right)-4x^2+8x-4=0\)

\(\Leftrightarrow x^2\left(x-1\right)-4\left(x-1\right)^2=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-2\right)^2=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)

\(\left(a^2-b^2\right)+\left(a^3+b^3\right)-a^2b^2\left(a+b\right)\)

\(=\left(a+b\right)\left(a-b\right)+\left(a+b\right)\left(a^2-ab+b^2\right)-a^2b^2\left(a+b\right)\)

\(=\left(a+b\right)\left(a-b+a^2+b^2-ab-a^2b^2\right)\)

\(=\left(a+b\right)\left[b^2\left(1-a^2\right)+a\left(1+a\right)-b.\left(1+a\right)\right]\)

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