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\(2x^3-12x^2+18x=2x\left(x^2-6x+9\right)=2x\left(x-3\right)^2\)
\(2x-x^2=2\\ \Leftrightarrow x^2-2x+2=0\\ \Leftrightarrow\left(x^2-2x+1\right)+1=0\\ \Leftrightarrow\left(x-1\right)^2+1=0\\ Mà:\left(x-1\right)^2\ge0\forall x\in R\\ \Rightarrow\left(x-1\right)^2+1\ge1\forall x\in R\\ Vậy:Pt.vô.nghiệm\\ x^3+15x^2+75x+125=0\\ x^3+3.x^2.5+3.x.5^2+5^3=0\\ \left(x+5\right)^3=0\\ \Leftrightarrow x+5=0\\ \Leftrightarrow x=-5\\ x^3+48x=12x^2+64\\ \Leftrightarrow x^3-12x^2+48x-64=0\\ \Leftrightarrow x^3-3.x^2.4+3.x.4^2-4^2=0\\ \Leftrightarrow\left(x-4\right)^3=0\\ \Leftrightarrow x-4=0\\ \Leftrightarrow x=4\)
1, \(xy^3-x^3y=xy\left(y^2-x^2\right)=xy\left(y-x\right)\left(x+y\right)\)
2, \(5x\left(3y+4x-6\right)\)
3, \(3x\left(2-y\right)\)
4, \(x\left(x^2+2x+1\right)=x\left(x+1\right)^2\)
5, \(x\left(4x^2-12x+9\right)=x\left(2x-3\right)^2\)
6, \(2xy\left(x+2y-5x^2y\right)\)
7, \(x^2\left(x^2+2x+1\right)=x^2\left(x+1\right)^2\)
11, \(\left(x+y\right)\left(x-1\right)\)
\(1,xy^3-x^3y=xy\left(y^2-x^2\right)=xy\left(y-x\right)\left(y+x\right)\\ 2,15xy+20x^2-30x=5x\left(3y+4x-6\right)\\ 3,6x-3xy=3x\left(2-y\right)\\ 4,x^3+2x^2+x=x\left(x^2+2x+1\right)=x\left(x+1\right)^2\\ 5,4x^3-12x^2+9x=x\left(4x^2-12x+9\right)=x\left(2x-3\right)^2\\ 6,2x^2y+4xy^2-10x^3y^2=2xy\left(x+2y-5x^2y\right)\\ 11,x\left(x-1\right)-y\left(1-x\right)=x\left(x-1\right)+y\left(x-1\right)=\left(x-1\right)\left(x+y\right)\)
Câu 1:
a) 2x(3x+2) - 3x(2x+3) = 6x^2+4x - 6x^2-9x = -5x
b) \(\left(x+2\right)^3+\left(x-3\right)^2-x^2\left(x+5\right)\)
\(=x^3+6x^2+12x+8+x^2-6x+9-x^3-5x^2\)
\(=2x^2+6x+17\)
c) \(\left(3x^3-4x^2+6x\right)\div\left(3x\right)=x^2-\dfrac{4}{3}x+2\)
\(\left(x+2\right)\left(x-3\right)\left(17x^2-17x+8\right)=\left(x+2\right)\left(x-3\right)\left(x^2-17x+33\right)\)
=>\(17x^2-17x+8=x^2-17x+33\)
<=> \(16x^2-25=0\)
<=>\(\left(4x-5\right)\left(4x+5\right)=0\)
=> \(4x-5=0=>x=\dfrac{5}{4}\)
hoặc \(4x+5=0=>x=\dfrac{-5}{4}\)
(x+2)(x−3)(17x2−17x+8)=(x+2)(x−3)(x2−17x+33)
\(\Leftrightarrow\)(x+2)(x−3)(17x2−17x+8) - (x+2)(x−3)(x2−17x+33) = 0
\(\Leftrightarrow\)(x+2)(x−3).[(17x2−17x+8)-(x2−17x+33)] = 0
\(\Leftrightarrow\)\(\left[{}\begin{matrix}\text{x+2 = 0}\\\text{x−3 = 0}\\\text{(17x^2−17x+8)-(x^2−17x+33) = 0}\end{matrix}\right.\)
\(\Leftrightarrow\)\(\left[{}\begin{matrix}x=-2\\x=3\\17x^2-17x+8-x^2+17x-33=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\\16x^2-25=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\\\left(4x-5\right)\left(4x+5\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\\4x-5=0\\4x+5=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\\4x=5\\4x=-5\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\\x=\dfrac{5}{4}\\x=\dfrac{-5}{4}\end{matrix}\right.\)
Vậy S = \(\left\{-2;\dfrac{-5}{4};\dfrac{5}{4};3\right\}\)
1.
\(\left(12x^2+6x\right)\left(y+z\right)+\left(12x^2+6x\right)\left(y-z\right)\\ =\left(12x^2+6x\right)\left(y+z+y-z\right)\\ =2y\left(12x^2+6x\right)\\ =2y.6x\left(2x+1\right)\\ =12xy\left(2x+1\right)\)
2.
\(x\left(x-6\right)+10\left(x-6\right)=0\\ \Leftrightarrow\left(x-6\right)\left(x+10\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=6\\x=-10\end{matrix}\right.\)
Vậy \(x\in\left\{6;-10\right\}\) là nghiệm của pt
Bài 1:
Ta có: \(\left(12x^2+6x\right)\left(y+z\right)+\left(12x^2+6x\right)\left(y-z\right)\)
\(=\left(12x^2+6x\right)\left(y+z+y-z\right)\)
\(=6x\left(2x+1\right)\cdot2y\)
\(=12xy\left(2x+1\right)\)
Bài 2:
Ta có: \(x\left(x-6\right)+10\left(x-6\right)=0\)
\(\Leftrightarrow\left(x-6\right)\left(x+10\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=6\\x=-10\end{matrix}\right.\)
\(2x^3-12x^2+17x-2\)
\(=2x^3-4x^2-8x^2+16x+x-2\)
\(=2x^2\left(x-2\right)-8x\left(x-2\right)+\left(x-2\right)\)
\(=\left(2x^2-8x+1\right)\left(x-2\right)\)
\(2x^3-12x^2+17x-2\)
\(=2x^3-8x^2-4x^2+x+16x-2\)
\(=\left(2x^3-8x^2+x\right)-\left(4x^2-16x+2\right)\)
\(=x\left(2x^2-8x+1\right)-2\left(2x^2-8x+1\right)\)
\(=\left(2x^2-8x+1\right)\left(x-2\right)\)