\(\frac{5xX}{X-13}=49x0,5-7x0,5+0,25\)
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Bài làm:
a) Ta có: \(\frac{5x}{x-13}=49.0,5-7.0,5+0,25\)
\(\Leftrightarrow\frac{5x}{x-13}=21,25\)
\(\Leftrightarrow5x=21,25x-276,25\)
\(\Leftrightarrow16,25x=276,25\)
\(\Rightarrow x=17\)
b) Ta có: \(B=\frac{202}{303}=\frac{2.101}{3.101}=\frac{2}{3}\)
\(C=\frac{6363}{8181}=\frac{7.909}{9.909}=\frac{7}{9}\)
mà \(\frac{8}{9}>\frac{7}{9}>\frac{2}{3}\Rightarrow A>C>B\)
Vậy A lớn nhất
Sa
#)Giải :
a) \(\frac{2xX-4,36}{0,125}=\)0,25 x 42,9 - 11,7 x 0,25 + 0,25 x 0,8
\(\frac{2xX-4,36}{0,125}=\)0,25 x ( 42,9 - 11,7 + 0,8 )
\(\frac{2xX-4,36}{0,125}=\)0,25 x 32
\(\frac{2xX-4,36}{0,125}=8\)
\(2xX-4,36=8x0,125\)
\(2xX-4,36=1\)
\(2xX=1+4,36\)
\(2xX=5,36\)
\(X=5,36:2\)
\(X=2,68\)
#~Will~be~Pens~#
chắc đề là như vậy: \(\frac{5x}{x-13}=21,25\)
=> \(21,23\left(x-13\right)=5x\)
=> \(21,23x-275,99=5x\)
=> \(21,23x-5x=275,99\)
=> \(16,23x=275,99\Rightarrow x=\frac{275,99}{16,23}=...\)
\(B=\frac{0,6-\frac{3}{11}+\frac{3}{13}}{1,4-\frac{7}{11}+\frac{7}{13}}-\frac{\frac{1}{3}-0,25+\frac{1}{5}}{1\frac{1}{6}-0,875+0,7}\)
\(B=\frac{\frac{3}{5}-\frac{3}{11}+\frac{3}{13}}{\frac{7}{5}-\frac{7}{11}+\frac{7}{13}}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(B=\frac{3\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}{5\left(\frac{1}{5}-\frac{1}{11}+\frac{1}{13}\right)}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{7\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{10}\right)}\)
\(B=\frac{3}{5}-\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{7.\frac{1}{2}\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}\)
\(B=\frac{3}{5}-\frac{2}{7}=\frac{11}{35}\)
\(\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{\frac{2}{3}-\frac{2}{7}-\frac{2}{13}}\cdot\frac{\frac{1}{3}-0,25+0,2}{1\frac{1}{6}-0,875+0,7}\)
\(=\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{2.\left(\frac{1}{3}-\frac{1}{7}-\frac{1}{13}\right)}\cdot\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}\)
\(=\frac{1}{2}\cdot\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}.\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}=\frac{1}{2}\cdot\frac{1}{\frac{7}{2}}=\frac{1}{2}\cdot\frac{2}{7}=\frac{1}{7}\)
\(\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{\frac{2}{3}-\frac{2}{7}-\frac{2}{13}}.\frac{\frac{1}{3}-0,25+0,2}{1\frac{1}{6}-0,875+0,7}+\frac{6}{7}\)
= \(\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{2\left(\frac{1}{3}-\frac{1}{7}-\frac{1}{13}\right)}.\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}+\frac{6}{7}\)
= \(\frac{1}{2}.\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{7.\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}+\frac{6}{7}\)
= \(\frac{1}{2}.\frac{1}{\frac{7}{2}}+\frac{6}{7}\)
= \(\frac{1}{2}.\frac{2}{7}+\frac{6}{7}\)
= \(\frac{1}{7}+\frac{6}{7}\)
= 1
\(=\frac{\frac{1}{3}-\frac{1}{7}-\frac{1}{13}}{2.\left(\frac{1}{3}-\frac{1}{7}-\frac{1}{13}\right)}.\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{6}-\frac{7}{8}+\frac{7}{10}}+\frac{6}{7}\)
\(=\frac{1}{2}.\frac{\frac{1}{3}-\frac{1}{4}+\frac{1}{5}}{\frac{7}{2}.\left(\frac{1}{3}-\frac{1}{4}+\frac{1}{5}\right)}+\frac{6}{7}\)
\(=\frac{1}{2}.\frac{2}{7}+\frac{6}{7}\)
\(=1\)
\(\frac{5\times x}{x-13}=49\times0,5-7\times0,5+0,25\)
\(\Rightarrow\frac{5\times x}{x-13}=0,5\times\left(49-7\right)+0,25\)
\(\Rightarrow\frac{5\times x}{x-13}=0,5\times42+0,25\)
\(\Rightarrow\frac{5\times x}{x-13}=21,25\)
\(\Rightarrow5\times x:x-13=21,25\)
\(\Rightarrow5\times1x=34,25\)
\(\Rightarrow1x=6,85\)
\(\Rightarrow x=6,85\)