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g: \(=\dfrac{x^2+2x-x^2-4x-2x+4}{x\left(x-2\right)\left(x+2\right)}=\dfrac{-4x+4}{x\left(x-2\right)\left(x+2\right)}\)
h: \(=\dfrac{2x^2+1-x^2+1-x^2+x-1}{\left(x+1\right)\left(x^2-x+1\right)}\)
\(=\dfrac{x+1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{1}{x^2-x+1}\)
\(e,=\dfrac{1}{x-1}-\dfrac{2x}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{x^2-2x+1}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{\left(x-1\right)^2}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{x-1}{x^2+1}\\ f,=\dfrac{3x-1}{2\left(3x+1\right)}+\dfrac{3x+1}{2\left(3x-1\right)}-\dfrac{6x}{\left(3x-1\right)\left(3x+1\right)}\\ =\dfrac{9x^2-6x+1+9x^2+6x+1-12x}{2\left(3x-1\right)\left(3x+1\right)}=\dfrac{2\left(3x-1\right)^2}{2\left(3x-1\right)\left(3x+1\right)}=\dfrac{3x-1}{3x+1}\)
\(g,=\dfrac{x}{x\left(x-2\right)}-\dfrac{x^2+4x}{x\left(x-2\right)\left(x+2\right)}-\dfrac{2}{x\left(x+2\right)}\\ =\dfrac{x^2+2x-x^2-4x-2x+4}{x\left(x-2\right)\left(x+2\right)}=\dfrac{-4x+4}{x\left(x-2\right)\left(x+2\right)}\\ h,=\dfrac{2x^2+1-x^2+1-x^2+x-1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{x+1}{\left(x+1\right)\left(x^2-x+1\right)}=\dfrac{1}{x^2-x+1}\)
Xét tứ giác ABEC có
O là trung điểm của BC
O là trung điểm của AE
Do đó: ABEC là hình bình hành
mà \(\widehat{CAB}=90^0\)
nên ABEC là hình chữ nhật
\(\dfrac{3}{4}\left(x^2y\right)^2:\dfrac{1}{8}xy^2\\ =\dfrac{3}{4}x^4y^2:\dfrac{1}{8}xy^2\\ =\left(\dfrac{3}{4}:\dfrac{1}{8}\right)\left(x^4:x\right)\left(y^2:y^2\right)\\ =6x^3\)
\(\dfrac{3}{4}\left(x^2y\right)^2\div\dfrac{1}{8}xy^2\)
\(=\dfrac{3}{4}x^4y^2\div\dfrac{1}{8}xy^2\)
\(=6x^3\)
Câu 2:
\(\Leftrightarrow\left(x+2\right)\left(10x+3\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=-\dfrac{3}{10}\end{matrix}\right.\)
Câu 19:
\(=\dfrac{11x+x-18}{2x-3}=\dfrac{12x-18}{2x-3}=6\)
Câu 20:
\(=\dfrac{3x+5}{x\left(x-5\right)}+\dfrac{x-25}{5\left(x-5\right)}\)
\(=\dfrac{15x+25+x^2-25x}{5x\left(x-5\right)}=\dfrac{\left(x-5\right)^2}{5x\left(x-5\right)}=\dfrac{x-5}{5x}\)
\(3.\)
\(a,\)
\(\left(2x-3\right)^2-\left(x+5\right)^2=0\)
\(\Leftrightarrow4x^2-12x+9-x^2-10x-25=0\)
\(\Leftrightarrow3x^2-22x-16=0\)
\(\Leftrightarrow3.\left(x-8\right)\left(x+\dfrac{2}{3}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3=0\left(\text{vô lí}\right)\\x-8=0\\x+\dfrac{2}{3}=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=8\\x=-\dfrac{2}{3}\end{matrix}\right.\)
Vậy \(S=\left\{8;-\dfrac{2}{3}\right\}\)
\(b,\)
\(\left(x^3-x^2\right)-4x^2+8x-4=0\)
\(\Leftrightarrow x^3-5x^2+8x-4=0\)
\(\Leftrightarrow\left(x-1\right)\left(x-2\right)^2=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\\left(x-2\right)^2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x-2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
Vậy \(S=\left\{1;2\right\}\)
\(4.\)
\(a,\)
\(16x^3y+\dfrac{1}{4}yz^3\)
\(=\dfrac{1}{4}y\left(64x^3+z^3\right)\)
\(=\dfrac{1}{4}y\left(4x+z\right)\left(16x^2-4xz+z^2\right)\)
\(b,\)
\(x^{m+4}-x^{m+3}-x-1\)
\(=x^m.x^4-x^m.x^3-x-1\)
\(=x^m.\left(x^4-x^3\right)-x-1\)
\(=x^m.x^3.\left(x+1\right)-\left(x+1\right)\)
\(=\left(x^{m+3}-1\right)\left(x+1\right)\)
3:
a: =>(2x-3-x-5)(2x-3+x+5)=0
=>(x-8)(3x+2)=0
=>x=8 hoặc x=-2/3
b: =>x^3-x^2-4(x-1)^2=0
=>x^2(x-1)-4(x-1)^2=0
=>(x-1)(x^2-4x+4)=0
=>x=1 hoặc x=2
Câu e,d à bạn