a) \(5x^2y-20xy+20y=5y\left(x^2-4x+4\right)=5y\left(x-2\right)^2\)

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

c) \(3x^2y-12y=3y\left(x^2-4\right)=3y\left(x-2\right)\left(x+2\right)\)

d) \(7x^3-28x^2+28x=7x\left(x^2-4x+4\right)=7x\left(x-2\right)^2\)

a: \(5x^2y-20xy+20y\)

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

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

b: \(3x^3+6x^2+3x\)

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

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

c: \(3x^2y-12y\)

\(=3y\left(x^2-4\right)\)

\(=3y\left(x-2\right)\left(x+2\right)\)

d: \(7x^3-28x^2+28x\)

\(=7x\left(x^2-4x+4\right)\)

\(=7x\left(x-2\right)^2\)

a: \(\Leftrightarrow\left(-x+3\right)\left(x+6\right)=18\)

\(\Leftrightarrow-x^2-6x+3x+18-18=0\)

\(\Leftrightarrow-x\left(x+3\right)=0\)

=>x=0 hoặc x=-3

b: \(\Leftrightarrow x\left(3x^2+6x-4\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\3x^2+6x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x^2+2x-\dfrac{4}{3}=0\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\\left(x+1\right)^2=\dfrac{7}{3}\end{matrix}\right.\Leftrightarrow x\in\left\{0;\dfrac{\sqrt{21}}{3}-1;\dfrac{-\sqrt{21}}{3}-1\right\}\)

c: =>x(3x-5)=0

=>x=0 hoặc x=5/3

d: =>(x-2)(x+2)=0

=>x=2 hoặc x=-2

       \(4x^4+4x^3+5x^2+2x+1\)

\(=\left(2x^2\right)^2+2.2x^2.x+x^2+4x^2+2x+1\)

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

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

       \(x^4+6x^3+11x^2+6x+1\)

\(=\left(x^2\right)^2+2.x^2.3x+\left(3x\right)^2+2x^2+6x+1\)

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

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

Chúc bạn học tốt.

a, x²-5x+6=(x²-2x)-(3x-6)=x(x-2)-3(x-2)=(x-2)(x-3)

b, 3x²+9x-30=(3x²-6x)+(15x-30)=3x(x-2)+15(x-2)=3(x-2)(x+5)

c, x²-3x+2=(x²-x)-(2x-2)=x(x-1)-2(x-1)=(x-1)(x-2)

a, x^2-5x+6=x^2-2x-3x+6=(x^2-2x)-(3x-6)=x(x-2)-3(x-2)=(x-3)(x-2)

b, 3x^2+9x-30=3x^2-6x+15x-30=(3x^2-6x)+(15x-30)=3x(x-2)+3(x-2)=(3x+3)(x-2)

c, x^2-3x+2=x^2-x-2x+2=(x^2-x)-(2x-2)=x(x-1)-2(x-1)=(x-2)(x-1)

câu b mik lm nhầm nhé

3x (5x² - 2x - 1)

12.C

13.C

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