tìm nghiệm của Pt \(\frac{x+1}{x-1}+\frac{x-2}{x+2}+\frac{x-3}{x+3}+\frac{x+4}{x-4}=4\)
B1 : cho PT : 2(x + 2 ) - 7 = 3 - x
a) x = -2 có phải là nghiệm của phương trình không ?
b) x = 2 có phải là nghiệm của phương trình không ?
B2 : giải PT :
a) (x -3 )( x - 4 ) - 2( 3x - 2 ) = ( x - 4 )2
b) \(\frac{3\left(2x+1\right)}{4}-\frac{5x+3}{6}=\frac{2x-1}{3}+\frac{7}{12}\)
giải pt
\(\frac{x+1}{x-1}+\frac{x-2}{x+2}+\frac{x-3}{x+3}+\frac{x+4}{x-4}=4\)
Sửa lại đề \(\frac{x+1}{x-1}+\frac{x-2}{x+2}+\frac{x-3}{x+3}+\frac{x+4}{x-4}=-4\)
ĐK \(x\ne\left\{1;-2;-3;4\right\}\)
\(\Leftrightarrow\left(\frac{x+1}{x-1}+1\right)+\left(\frac{x-2}{x+2}+1\right)+\left(\frac{x-3}{x+3}+1\right)+\left(\frac{x+4}{x-4}+1\right)=0\)
\(\Leftrightarrow\frac{2x}{x-1}+\frac{2x}{x+2}+\frac{2x}{x+3}+\frac{2x}{x-4}=0\)
\(\Leftrightarrow2x\left(\frac{1}{x-1}+\frac{1}{x+2}+\frac{1}{x+3}+\frac{1}{x-4}\right)=0\Leftrightarrow x=0\)vì \(\frac{1}{x-1}+\frac{1}{x+2}+\frac{1}{x+3}+\frac{1}{x-4}\ne0\)
Vậy pt có nghiệm \(x=0\)
cô giáo in đề cho mk là =4 mà
nếu k thì mk xong lâu r
BT: giải các pt sau
1. \(\frac{x+1}{2013}+\frac{x+2}{2012}=\frac{x+3}{2011}+\frac{x+4}{2010}\)
2. \(\frac{3x+2}{4}+\frac{x+3}{2}=\frac{x-1}{3}-\frac{-x-1}{12}\)
3.\(\frac{x+1}{x-1}-\frac{x-1}{x+1}+\frac{x^2+3}{1-x^2}=0\)
4. \(\frac{1}{x+2}-\frac{3x}{x-2}=\frac{16}{x^2-4}\)
1.\(\frac{x+1}{2013}\)+\(\frac{x+2}{2012}\)=\(\frac{x+3}{2011}\)+\(\frac{x+4}{2010}\)
⇔\(\frac{x+1}{2013}\)+1+\(\frac{x+2}{2012}\)+1=\(\frac{x+3}{2011}\)+1+\(\frac{x+4}{2010}\)+1
⇔\(\frac{x+2014}{2013}\)+\(\frac{x+2014}{2012}\)=\(\frac{x+2014}{2011}\)+\(\frac{x+2014}{2010}\)
⇔\(\frac{x+2014}{2013}\)+\(\frac{x+2014}{2012}\)-\(\frac{x+2014}{2011}\)-\(\frac{x+2014}{2010}\)=0
⇔(x+2014)(\(\frac{1}{2013}\)+\(\frac{1}{2012}\)-\(\frac{1}{2011}\)-\(\frac{1}{2010}\))=0
Mà \(\frac{1}{2013}\)+\(\frac{1}{2012}\)-\(\frac{1}{2011}\)-\(\frac{1}{2010}\)≠0
⇔x+2014=0
⇔x=-2014
Vậy tập nghiệm của phương trình đã cho là:S={-2014}
2.\(\frac{3x+2}{4}\)+\(\frac{x+3}{2}\)=\(\frac{x-1}{3}\)-\(\frac{-x-1}{12}\)
⇔\(\frac{3\left(3x+2\right)}{12}\)+\(\frac{6\left(x+3\right)}{12}\)=\(\frac{4\left(x-1\right)}{12}\)+\(\frac{x+1}{12}\)
⇒9x+6+6x+18=4x-4+x+1
⇒15x+24=5x-3
⇒15x-5x=-3-24
⇒10x=-27
⇒ x=-\(\frac{27}{10}\)
Vậy tập nghiệm của phương trình đã cho là S={-\(\frac{27}{10}\)}
\(3.\frac{x+1}{x-1}-\frac{x-1}{x+1}+\frac{x^2+3}{1-x^2}=0ĐKXĐ:x\ne\pm1\)
\(\frac{1+x}{x-1}-\frac{x-1}{1+x}+\frac{x^2+3}{\left(1+x\right)\left(1-x\right)}=0\)
\(-3+7x-5x^2+x^3=0\)
\(\left(x-3\right)\left(x-1\right)\left(x-1\right)=0\)
\(\left[{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)Theo ĐKXĐ => x=3
Nghiệm nhỏ nhất của pt\(\frac{1}{2\sqrt{x}-2014}+\frac{1}{3\sqrt{x}+2013}=\frac{1}{2015-4\sqrt{x}}+\frac{1}{9\sqrt{x}-2016}\)
1) tìm m để pt sau có 2 nghiệm \(x+\sqrt{x+\frac{1}{2}+\sqrt{x+\frac{1}{4}}}=m\)
2) tìm m để pt sau có 1 nghiệm
a) \(\sqrt{x+1}-m\sqrt{x-1}+2\sqrt[4]{x^2-1}=0\)
b) \(\sqrt{\frac{x-1}{x+2}}-m\sqrt{\frac{x+2}{x-1}}+2=0\)
1/ \(x+\sqrt{x+\frac{1}{2}+\sqrt{x+\frac{1}{4}}}=x+\sqrt{\left(x+\frac{1}{4}\right)+\sqrt{x+\frac{1}{4}}+\frac{1}{4}}\)
\(=x+\sqrt{\left(\sqrt{x+\frac{1}{4}}+\frac{1}{2}\right)^2}=x+\left|\sqrt{x+\frac{1}{4}}+\frac{1}{2}\right|=\left(x+\frac{1}{4}\right)+\sqrt{x+\frac{1}{4}}+\frac{1}{4}\)
\(=\left(\sqrt{x+\frac{1}{4}}+\frac{1}{2}\right)^2\)
\(\Rightarrow m=\left(\sqrt{x+\frac{1}{4}}+\frac{1}{2}\right)^2\)
Để pt trên có nghiệm thì \(\hept{\begin{cases}m>0\\\sqrt{m}-\frac{1}{2}\ge0\end{cases}}\Leftrightarrow\hept{\begin{cases}m>0\\m\ge\frac{1}{4}\end{cases}}\Leftrightarrow m\ge\frac{1}{4}\)
Vậy với \(m\ge\frac{1}{4}\) thì pt trên có nghiệm.
Phương trình trên chỉ có một nghiệm thôi nhé, đó là \(x=m-\sqrt{m}\) với \(m\ge\frac{1}{4}\)
cậu lm đc bài 2 câu a ko.. mk còn mỗi câu đấy
1. Giải PT sau
a) \(\left(\frac{x-1}{x+1}\right)^2-4\left(\frac{x^2-1}{x^2-4}\right)+3\left(\frac{x+1}{x-2}\right)^2=0\)
b) \(\frac{x^2}{3}+\frac{48}{x^2}=10\left(\frac{x}{3}-\frac{4}{x}\right)\)
Giải pt:
1. x-4=2x+4
2. \(\frac{2x-1}{2}-\frac{x}{3}=x-\frac{x}{6}\)
3.\(\frac{x+3}{2x+1}-\frac{x}{x-3}=\frac{3x^2+x+9}{\left(2x+1\right)\left(x-3\right)}\)
4.\(\frac{2x}{3}+\frac{2x-1}{6}=4-\frac{x}{3}\)
1) Ta có: x-4=2x+4
\(\Leftrightarrow x-4-2x-4=0\)
\(\Leftrightarrow-x-8=0\)
\(\Leftrightarrow-x=8\)
hay x=-8
Vậy: S={8}
2) Ta có: \(\frac{2x-1}{2}-\frac{x}{3}=x-\frac{x}{6}\)
\(\Leftrightarrow\frac{3\left(2x-1\right)}{6}-\frac{2x}{6}=\frac{6x}{6}-\frac{x}{6}\)
\(\Leftrightarrow3\left(2x-1\right)-2x-6x+x=0\)
\(\Leftrightarrow6x-3-2x-6x+x=0\)
\(\Leftrightarrow-x-3=0\)
\(\Leftrightarrow-x=3\)
hay x=-3
Vậy: S={-3}
3) ĐKXĐ: \(x\notin\left\{\frac{-1}{2};3\right\}\)
Ta có: \(\frac{x+3}{2x+1}-\frac{x}{x-3}=\frac{3x^2+x+9}{\left(2x+1\right)\left(x-3\right)}\)
\(\Leftrightarrow\frac{\left(x+3\right)\left(x-3\right)}{\left(2x+1\right)\left(x-3\right)}-\frac{x\left(2x+1\right)}{\left(x-3\right)\left(2x+1\right)}=\frac{3x^2+x+9}{\left(2x+1\right)\left(x-3\right)}\)
Suy ra: \(x^2-9-\left(2x^2+x\right)-3x^2-x-9=0\)
\(\Leftrightarrow-2x^2-x-18-2x^2-x=0\)
\(\Leftrightarrow-4x^2-2x-18=0\)
\(\Leftrightarrow-4\left(x^2+\frac{1}{2}x+\frac{4}{5}\right)=0\)
\(\Leftrightarrow x^2+\frac{1}{2}x+\frac{4}{5}=0\)
\(\Leftrightarrow x^2+2\cdot x\cdot\frac{1}{4}+\frac{1}{16}+\frac{59}{80}=0\)
\(\Leftrightarrow\left(x+\frac{1}{4}\right)^2+\frac{59}{80}=0\)(vô lý)
Vậy: S=\(\varnothing\)
4) Ta có: \(\frac{2x}{3}+\frac{2x-1}{6}=4-\frac{x}{3}\)
\(\Leftrightarrow\frac{4x}{6}+\frac{2x-1}{6}=\frac{24}{6}-\frac{2x}{6}\)
\(\Leftrightarrow4x+2x-1=24-2x\)
\(\Leftrightarrow6x-1-24+2x=0\)
\(\Leftrightarrow8x-25=0\)
\(\Leftrightarrow8x=25\)
hay \(x=\frac{25}{8}\)
Vậy: \(S=\left\{\frac{25}{8}\right\}\)
Giải pt: \(\frac{x+1}{x-1}+\frac{x-2}{x+2}+\frac{x-3}{x+3}+\frac{x+4}{x-4}=4\)
Giải pt
\(\frac{x^2+x+1}{x+1}+\frac{x^2+2x+2}{x+2}=\frac{x^2+3x+3}{x+3}+\frac{x^2+4x+4}{x+4}\)
\(x\ne\left\{-4;-3;-2;-1\right\}\)
\(\Leftrightarrow\frac{x^2+x+1}{x+1}-1+\frac{x^2+2x+2}{x+2}-1=\frac{x^2+3x+3}{x+3}-1+\frac{x^2+4x+4}{x+4}-1\)
\(\Leftrightarrow\frac{x^2}{x+1}+\frac{x^2+x}{x+2}-\frac{x^2+2x}{x+3}-\frac{x^2+3x}{x+4}=0\)
\(\Leftrightarrow x\left(\frac{x}{x+1}+\frac{x+1}{x+2}-\frac{x+2}{x+3}-\frac{x+3}{x+4}\right)=0\)
\(\Leftrightarrow x\left(1-\frac{1}{x+1}+1-\frac{1}{x+2}+\frac{1}{x+3}-1+\frac{1}{x+4}-1\right)=0\)
\(\Leftrightarrow x\left(\frac{1}{x+3}+\frac{1}{x+4}-\frac{1}{x+1}-\frac{1}{x+2}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\\frac{1}{x+3}-\frac{1}{x+1}=\frac{1}{x+2}-\frac{1}{x+4}\left(1\right)\end{matrix}\right.\)
\(\left(1\right)\Leftrightarrow\frac{-2}{\left(x+1\right)\left(x+3\right)}=\frac{2}{\left(x+2\right)\left(x+4\right)}\)
\(\Leftrightarrow\left(x+2\right)\left(x+4\right)+\left(x+1\right)\left(x+3\right)=0\)
\(\Leftrightarrow2x^2+10x+11=0\Rightarrow x=\frac{-5\pm\sqrt{3}}{2}\)