M=\(\dfrac{|x+1|+2x}{3x^2-2x-1}\)
Rút gọn M
Cho biểu thức: \(M=\left(\dfrac{1+2x}{4+2x}-\dfrac{x}{3x-6}+\dfrac{2x^2}{12-3x^2}\right).\dfrac{24+12x}{6+13x}\). Rút gọn M
Rút gọn M và A sau đây :
M= \(\left(\dfrac{x}{x+3}+\dfrac{3-x}{x+3}.\dfrac{x^2+3x+9}{x^2-9}\right)\)
A= \(\left(\dfrac{3x}{1-3x}-\dfrac{2x}{3x+1}\right):\dfrac{6x^2+10x}{1-6x+9x^2}\)
rút gọn biểu thức:
a) \(\dfrac{2x^{2^{ }}-2x}{x-1}\)
b)\(\dfrac{x^{2^{ }}+2x+1}{3x^2+3x}\)
c)\(\dfrac{x}{3x-3}+\dfrac{1}{x^2-1}\)
a) Ta có: \(\dfrac{2x^2-2x}{x-1}\)
\(=\dfrac{2x\left(x-1\right)}{x-1}\)
=2x
b) Ta có: \(\dfrac{x^2+2x+1}{3x^2+3x}\)
\(=\dfrac{\left(x+1\right)^2}{3x\left(x+1\right)}\)
\(=\dfrac{x+1}{3x}\)
c) Ta có: \(\dfrac{x}{3x-3}+\dfrac{1}{x^2-1}\)
\(=\dfrac{x}{3\left(x-1\right)}+\dfrac{1}{\left(x-1\right)\left(x+1\right)}\)
\(=\dfrac{x+1+3}{3\left(x-1\right)\left(x+1\right)}\)
\(=\dfrac{x+4}{3x^2-3}\)
a, \(\dfrac{2x^2-2x}{x-1}=\dfrac{2x\left(x-1\right)}{x-1}=2x\) ( đk : \(x\ne1\) )
b,\(\dfrac{x^2+2x+1}{3x^2+3x}=\dfrac{\left(x+1\right)^2}{3x\left(x+1\right)}=\dfrac{x+1}{3x}\) ( đk : \(x\ne-1\) )
c
=
rút gọn \(\dfrac{1}{x}\)-\(\dfrac{x}{2x+1}\)+\(\dfrac{2x^2-3x-1}{x\left(2x+1\right)}\)
=\(\dfrac{2x+1}{x\left(2x+1\right)}\)-\(\dfrac{x^2}{x\left(2x+1\right)}\)+\(\dfrac{2x^2-3x-1}{x\left(2x+1\right)}\)
= 2x+1 - x2 + 2x2-3x-1
= -x + x2
ĐKXĐ : x ≠ 0 ; x ≠ \(-\dfrac{1}{2}\)
\(\Rightarrow2x+1-x^2=2x^2-3x-1\)
\(\Leftrightarrow-3x^2+5x+2=0\)
\(\Leftrightarrow-3x^2-x+6x+2=0\)
\(\Leftrightarrow-x\left(3x+1\right)+2\left(3x+1\right)=0\)
\(\Leftrightarrow\left(3x+1\right)\left(-x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{3}\\x=2\end{matrix}\right.\) (N)
BÀI 6 :rút gọn phân thức
\(\dfrac{x^3+3x^3+3x+1}{x^2+x}\)
b)\(\dfrac{x^3-3x^2+3x-1}{2x-2}\)
c)\(\dfrac{x^2+4x+4}{2x+4}\)
d)\(\dfrac{(x-1)(-x-2)}{x+2}\)
e)\(\dfrac{x^2-y^2}{x+y}\)
f)\(\dfrac{3x^2+4xy^2}{6x+8y}\)
g)\(\dfrac{-3x^2-6x}{4-x^2}\)
BÀI 7 :quy đồng mẫu thức các phân thức
\(\dfrac{2}{5x^3y^2}và \dfrac{3}{4xy}\)
b)\(\dfrac{x}{x^2-2xy+y^2} và \dfrac{x}{x^2-xy}\)
c)\(\dfrac{1}{x+2};\dfrac{2}{2x+4}và \dfrac{3}{3x+6}\)
d)\(\dfrac{1}{x+3};\dfrac{2}{2x-6}và \dfrac{3}{3x-9}\)
6:
a: ĐKXĐ: x<>0
\(\dfrac{x^3+3x^2+3x+1}{x^2+x}\)
\(=\dfrac{\left(x+1\right)^3}{x\left(x+1\right)}=\dfrac{\left(x+1\right)^2}{x}\)
b: ĐKXĐ: x<>1
\(\dfrac{x^3-3x^2+3x-1}{2x-2}\)
\(=\dfrac{\left(x-1\right)^3}{2\left(x-1\right)}=\dfrac{\left(x-1\right)^2}{2}\)
c: ĐKXĐ: x<>-2
\(\dfrac{x^2+4x+4}{2x+4}\)
\(=\dfrac{\left(x+2\right)^2}{2\left(x+2\right)}\)
\(=\dfrac{x+2}{2}\)
d: ĐKXĐ: x<>-2
\(\dfrac{\left(x-1\right)\left(-x-2\right)}{x+2}\)
\(=\dfrac{\left(-x+1\right)\left(x+2\right)}{x+2}=-x+1\)
e: ĐKXĐ: x<>-y
\(\dfrac{x^2-y^2}{x+y}=\dfrac{\left(x-y\right)\left(x+y\right)}{x+y}=x-y\)
g: ĐKXĐ: \(x\notin\left\{2;-2\right\}\)
\(\dfrac{-3x^2-6x}{4-x^2}=\dfrac{3x^2+6x}{x^2-4}\)
\(=\dfrac{3x\left(x+2\right)}{\left(x+2\right)\cdot\left(x-2\right)}=\dfrac{3x}{x-2}\)
7:
a: \(\dfrac{2}{5x^3y^2}=\dfrac{2\cdot4}{20x^3y^2}=\dfrac{8}{20x^3y^2}\)
\(\dfrac{3}{4xy}=\dfrac{3\cdot5\cdot x^2y}{20x^3y^2}=\dfrac{15x^2y}{20x^3y^2}\)
b: \(\dfrac{x}{x^2-2xy+y^2}=\dfrac{x}{\left(x-y\right)^2}\)
\(\dfrac{x}{x^2-xy}=\dfrac{x}{x\left(x-y\right)}=\dfrac{1}{x-y}=\dfrac{\left(x-y\right)}{\left(x-y\right)^2}\)
c: \(\dfrac{1}{x+2}=\dfrac{6}{6\left(x+2\right)}\)
\(\dfrac{2}{2x+4}=\dfrac{2}{2\left(x+2\right)}=\dfrac{1}{x+2}=\dfrac{6}{6\left(x+2\right)}\)
\(\dfrac{3}{3x+6}=\dfrac{3}{3\left(x+2\right)}=\dfrac{6}{6\left(x+2\right)}\)
d:
\(\dfrac{2}{2x-6}=\dfrac{2}{2\left(x-3\right)}=\dfrac{1}{x-3};\dfrac{3}{3x-9}=\dfrac{3}{3\left(x-3\right)}=\dfrac{1}{x-3}\)
\(\dfrac{2}{2x-6}=\dfrac{1}{x-3}=\dfrac{x+3}{\left(x-3\right)\left(x+3\right)}\)
\(\dfrac{3}{3x-9}=\dfrac{1}{x-3}=\dfrac{x+3}{\left(x-3\right)\left(x+3\right)}\)
\(\dfrac{1}{x+3}=\dfrac{x-3}{\left(x+3\right)\left(x-3\right)}\)
Rút gọn A= \(\dfrac{1}{x}\)-\(\dfrac{x}{2x+1}\)+\(\dfrac{2x^2-3x-1}{x\left(2x+1\right)}\) x≠0,\(\dfrac{1}{2}\),1
Help
\(A=\dfrac{2x+1}{x\left(2x+1\right)}-\dfrac{x^2}{x\left(2x+1\right)}+\dfrac{2x^2-3x-1}{x\left(2x+1\right)}\)
\(=\dfrac{2x+1-x^2+2x^2-3x-1}{x\left(2x+1\right)}\)
\(=\dfrac{x^2-x}{x\left(2x+1\right)}=\dfrac{x\left(x-1\right)}{x\left(2x+1\right)}\)
\(=\dfrac{x-1}{2x+1}\)
\(=\dfrac{2x+1}{x\left(2x+1\right)}-\dfrac{x^2}{x\left(2x+1\right)}+\dfrac{2x^2-3x-1}{x\left(2x+1\right)}\)
\(=\dfrac{2x+1-x^2+2x^2-3x-1}{x\left(2x+1\right)}\)
\(=\dfrac{x^2+x}{x\left(2x+1\right)}\)
\(=\dfrac{x-1}{2x+1}\).
cho b.thức \(\dfrac{1-3x}{2x}+\dfrac{3x-2}{2x-1}+\dfrac{3x-2}{2x-4x^2}\)
hãy tính rút gọn rồi tính giá trị của b.thức tại x=\(\dfrac{1}{966}\)
Đặt `A=(1-3x)/(2x)+(3x-2)/(2x-1)+(3x-2)/(2x-4x^2)`
`=(2x(3x-2))/(2x(2x-1))-((3x-1)(2x-1))/(2x(2x-1))-(3x-2)/(2x(2x-1))`
`=(6x^2-4x-6x^2+5x-1-3x+2)/(2x(2x-1))`
`=(-2x+1)/(2x(2x-1))`
`=-1/(2x)`
`2x=1/(483)`
`=>A=-1/(1/483)=-483`
\(\dfrac{1-3x}{2x}+\dfrac{3x-2}{2x-1}+\dfrac{3x-2}{2x-4x^2}\)
⇔\(\dfrac{1-3x}{2x}+\dfrac{3x-2}{2x-1}+\dfrac{3x-2}{2x\left(1-2x\right)}\)
⇔\(\dfrac{1-3x}{2x}+\dfrac{3x-2}{2x-1}-\dfrac{(3x-2)}{2x\left(2x-1\right)}\)
ĐKXĐ: \(\left\{{}\begin{matrix}2x\ne0\\2x-1\ne0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne0\\2x\ne1\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x\ne0\\x\ne\dfrac{1}{2}\end{matrix}\right.\)
MTC: 2x(2x-1)
\(\dfrac{1-3x\left(2x-1\right)}{2x\left(2x-1\right)}+\dfrac{(3x-2)(2x)}{(2x-1)(2x)}-\dfrac{(3x-2)}{2x\left(2x-1\right)}\)
\(\Rightarrow1-3x\left(2x-1\right)+\left(3x-2\right)\left(2x\right)-\left(3x-2\right)\)
\(\Leftrightarrow1-6x^2+3x+6x^2-4x-3x+2\\ \Rightarrow-4x+3\)
Thay \(x=\dfrac{1}{966}\)vào biểu thức trên
ta có -4x+3= \(-4\times\dfrac{1}{966}+3=\dfrac{-4}{966}+3=\dfrac{-2}{483}+3=\dfrac{-2}{483}+\dfrac{1449}{483}=\dfrac{1447}{483}\)
Rút gọn A = \(\dfrac{3x}{x-1}\)+\(\dfrac{2}{x+1}\)+\(\dfrac{3-3x-2x^2}{x^2-1}\)
\(A=\dfrac{3x}{x-1}+\dfrac{2}{x+1}+\dfrac{3-3x-2x^2}{x^2-1}.\) \(\left(ĐKXĐ:x\ne1;x\ne-1\right).\)
\(A=\dfrac{3x\left(x+1\right)+2\left(x-1\right)+3-3x-2x^2}{\left(x-1\right)\left(x+1\right)}.\)
\(A=\dfrac{3x^2+3x+2x-2+3-3x-2x^2}{\left(x-1\right)\left(x+1\right)}.\)
\(A=\dfrac{x^2+2x+1}{\left(x-1\right)\left(x+1\right)}=\dfrac{\left(x+1\right)^2}{\left(x-1\right)\left(x+1\right)}=\dfrac{x+1}{x-1}.\)
A=\(\left(\dfrac{x-1}{x^2-2x}+\dfrac{x+1}{x^2+2x}-\dfrac{4}{x^3-4x}\right)\div\dfrac{2x+4}{x^2-3x}\)
Rút gọn A
\(A=\left(\dfrac{x-1}{x\left(x-2\right)}+\dfrac{x+1}{x\left(x+2\right)}-\dfrac{4}{x\left(x-2\right)\left(x+2\right)}\right)\cdot\dfrac{x\left(x-3\right)}{2\left(x+2\right)}\)
\(=\dfrac{x^2+x-2+x^2-x+2-4}{x\left(x-2\right)\left(x+2\right)}\cdot\dfrac{x\left(x-3\right)}{2\left(x+2\right)}\)
\(=\dfrac{2x^2-4}{x\left(x-2\right)\left(x+2\right)}\cdot\dfrac{x\left(x-3\right)}{2\left(x+2\right)}\)
\(=\dfrac{2x\left(x^2-2\right)\left(x-3\right)}{2x\left(x-2\right)\cdot\left(x+2\right)^2}=\dfrac{\left(x^2-2\right)\left(x-3\right)}{\left(x-2\right)\left(x+2\right)^2}\)
Rút gọn biểu thức M = \(\dfrac{x^2+5x+6+x\sqrt{9-x^2}}{3x-x^2+\left(x+2\right)\sqrt{9-x^2}}:2\sqrt{1+\dfrac{2x}{3-x}}\)
\(M=\dfrac{\left(x+2\right)\left(x+3\right)+x\sqrt{\left(3-x\right)\left(3+x\right)}}{x\left(3-x\right)+\left(x+2\right)\sqrt{\left(3-x\right)\left(3+x\right)}}:2\sqrt{\dfrac{3-x+2x}{3-x}}\left(-3\le x< 3;x\ne-1\right)\\ M=\dfrac{\sqrt{x+3}\left(x+2+x\sqrt{3-x}\right)}{\sqrt{3-x}\left[x+\left(x+2\right)\sqrt{3+x}\right]}:2\sqrt{\dfrac{x+3}{3-x}}\\ M=\dfrac{\sqrt{x+3}\left(x+2+x\sqrt{3-x}\right)}{\sqrt{3-x}\left[x+\left(x+2\right)\sqrt{3+x}\right]}\cdot\dfrac{3-x}{2\sqrt{\left(3-x\right)}\sqrt{\left(x+3\right)}}\)
\(M=\dfrac{x+2+x\sqrt{3-x}}{x+\left(x+2\right)\sqrt{3-x}}\cdot\dfrac{\sqrt{3-x}}{2\sqrt{3-x}}\\ M=\dfrac{\left(x+2\right)\sqrt{3-x}+x\left(3-x\right)}{2x\sqrt{3-x}+2\left(x+2\right)\sqrt{3-x}}\\ M=\dfrac{\sqrt{3-x}\left(2x+2\right)}{\sqrt{3-x}\left(2x+2x+4\right)}=\dfrac{2\left(x+1\right)}{4\left(x+1\right)}=\dfrac{1}{2}\)