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\(\frac{x+2}{327}+\frac{x+3}{326}+\frac{x+4}{325}+\frac{x+5}{324}+\frac{x+349}{5}=0\)
\(\Leftrightarrow\)\(\frac{x+2}{327}+1+\frac{x+3}{326}+1+\frac{x+4}{325}+1+\frac{x+5}{324}+1 +\frac{x+349}{5}-4=0\)
\(\Leftrightarrow\)\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)
\(\Leftrightarrow\)\(\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)
\(\Leftrightarrow\)\(x+329=0\) (vì 1/327 + 1/326 + 1/325 + 1/324 + 1/5 khác 0 )
\(\Leftrightarrow\)\(x=-329\)
Bài 1 :
\(\frac{x+2}{327}+\frac{x+3}{326}+\frac{x+4}{325}+\frac{x+5}{324}+\frac{x+349}{5}=0\)
\(\Leftrightarrow\)\(\left(\frac{x+2}{327}+1\right)+\left(\frac{x+3}{326}+1\right)+\left(\frac{x+4}{325}+1\right)+\left(\frac{x+5}{324}+1\right)+\left(\frac{x+349}{5}-4\right)=0\)
\(\Leftrightarrow\)\(\frac{x+329}{327}+\frac{x+329}{326}+\frac{x+329}{325}+\frac{x+329}{324}+\frac{x+329}{5}=0\)
\(\Leftrightarrow\)\(\left(x+329\right)\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)=0\)
Vì \(\left(\frac{1}{327}+\frac{1}{326}+\frac{1}{325}+\frac{1}{324}+\frac{1}{5}\right)\ne0\)
\(\Rightarrow\)\(x+329=0\)
\(\Rightarrow\)\(x=-329\)
Vậy \(x=-329\)
ĐK: \(x\ne\left\{1;3;8;20\right\}\)
\(\frac{2}{\left(x-1\right)\left(x-3\right)}+\frac{5}{\left(x-3\right)\left(x-8\right)}+\frac{12}{\left(x-8\right)\left(x-20\right)}-\frac{1}{x-20}=-\frac{3}{4}\)
\(\Leftrightarrow\)\(\frac{1}{x-3}-\frac{1}{x-1}+\frac{1}{x-8}-\frac{1}{x-3}+\frac{1}{x-20}-\frac{1}{x-8}-\frac{1}{x-20}=-\frac{3}{4}\)
\(\Leftrightarrow\)\(\frac{1}{x-1}=\frac{3}{4}\)
\(\Rightarrow\)\(x-1=\frac{4}{3}\)
\(\Leftrightarrow\)\(x=\frac{7}{3}\)(t/m)
Vậy...
Câu 1: \(B.\frac{5}{8}\)
Câu 2: \(C.x=20;y=12\)
Câu 3: \(B.\frac{1}{4}\)
đáp số \(:\frac{217}{50}\)
giải thích các bước giải
\(\left(3\frac{1}{2}-x\right)\)\(.1\frac{1}{4}\)\(=-1\frac{1}{20}\)\(=-\frac{21}{20}\)
\(\left(\frac{7}{2}-x\right)\)\(\frac{.5}{4}\)\(=-\frac{21}{20}\)
\(\frac{7}{2}\)\(-x=-\frac{21}{20}\)\(:\frac{5}{4}\)\(=-\frac{21}{20}\)\(.\frac{4}{5}\)\(=-\frac{21}{25}\)
\(x=\frac{7}{2}\)\(--\frac{21}{25}\)\(=\frac{7}{2}\)\(+\frac{21}{25}\)\(=\frac{175}{50}\)\(+\frac{42}{50}\)\(=\frac{217}{50}\)
{31/2-x] . 11/4 = -11/20
31/2-x=-11/20:11/4
31/2-x=-1/5
x=31/2-[-1/5]
x=157/10