x^2/6=24/25
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\(\dfrac{x^2}{6}=\dfrac{24}{25}\)
\(\Leftrightarrow x^2=\dfrac{144}{25}\)
hay \(x\in\left\{\dfrac{12}{5};-\dfrac{12}{5}\right\}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(x^2=\frac{144}{25}=\left(\frac{12}{5}\right)^2\Leftrightarrow\orbr{\begin{cases}x=\frac{12}{5}\\x=-\frac{12}{5}\end{cases}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{x^2}{6}=\dfrac{24}{25}\)
\(\Rightarrow x^2=\dfrac{24.6}{25}=\dfrac{144}{25}\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{12}{5}\\x=-\dfrac{12}{5}\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a) ĐKXĐ: \(x\ne-5\)
\(\Leftrightarrow7x-7=6x+30\\ \Leftrightarrow x=37\)
b) \(\Leftrightarrow25x^2=144\\ \Leftrightarrow x^2=\dfrac{144}{25}\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{12}{5}\\x=-\dfrac{12}{5}\end{matrix}\right.\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{x^2}{6}=\frac{24}{25}\)
=> x2.25 = 6 . 24
=> x2 . 25 = 144
=> x2 = 144 : 25
=> x2 = 5,76 = 2,42 = (-2,4)2
=> x \(\in\){2,4 ; -2,4}
\(\frac{x^2}{6}=\frac{24}{25}\Rightarrow25x^2=24.6\Rightarrow25x^2=144\Rightarrow x^2=\frac{144}{25}=\left(\frac{12}{5}\right)^2=\left(-\frac{12}{5}\right)^2\)
=> x = 12/5 hoặc x = -12/5
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giải biểu thức sau:
(1/7+1/91+1/24+1/475).25/24.x+30%=1/2
(1/6+1/66+1/176+1/336+1/546).26/25.x+30%=1/2
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1
a) \(5\times72\times10\times2=\left(5\times2\times10\right)\times72=100\times72=7200\)
b) \(40\times125=5\times\left(8\times125\right)=5\times1000=5000\)
c) \(16\times6\times25=4\times4\times6\times25=\left(4\times6\right)\times\left(4\times25\right)=24\times100=2400\) Bài 2:
a) \(24\times57+43\times24=24\times\left(57+43\right)=24\times100=2400\)
b) \(12\times19+80\times12+12=12\times\left(19+80+1\right)=12\times100=1200\)
c) \(\left(36\times15\times169\right)\div\left(5\times18\times13\right)\)
\(=\left(18\times2\times3\times5\times13\times13\right)\div\left(5\times18\times13\right)\)
\(=\left(2\times3\times13\right)\times\left(18\times5\times13\right)\div\left(5\times18\times13\right)\)
\(=2\times3\times13\)
\(=78\)
d) \(\left(44\times52\times60\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times11\times4\times13\times4\times15\right)\div\left(11\times13\times15\right)\)
\(=\left(4\times4\times4\right)\times\left(11\times13\times15\right)\div\left(11\times13\times15\right)\)
\(=4\times4\times4\)
\(=64\)
Bài 3:
a) \(x-280\div35=5\times54\)
\(x-8=270\)
\(x=270+8\)
\(x=278\)
b) \(\left(x-280\right)\div35=54\div4\)
\(\left(x-280\right)\div35=\dfrac{27}{2}\)
\(x-280=\dfrac{27}{2}\times35\)
\(x-280=\dfrac{945}{2}\)
\(x=\dfrac{945}{2}+280\)
\(x=\dfrac{1505}{2}\)
c) \(\left(x-128+20\right)\div192=0\)
\(x-128+20=0\times192\)
\(x-128+20=0\)
\(x-128=0-20\)
\(x-128=-20\)
\(x=-20+128\)
\(x=108\)
d) \(4\times\left(x+200\right)=460+85\times4\)
\(4\times\left(x+200\right)=460+340\)
\(4\times\left(x+200\right)=800\)
\(x+200=800\div4\)
\(x+200=200\)
\(x=200-200\)
\(x=0\)
Bài 4:
a) \(\dfrac{7}{12}-\dfrac{5}{12}=\dfrac{2}{12}=\dfrac{1}{6}\)
b) \(\dfrac{8}{11}+\dfrac{19}{11}=\dfrac{27}{11}\)
c) \(\dfrac{3}{8}+\dfrac{5}{12}=\dfrac{9}{24}+\dfrac{10}{24}=\dfrac{19}{24}\)
d) \(\dfrac{3}{4}+\dfrac{7}{12}=\dfrac{9}{12}+\dfrac{7}{12}=\dfrac{16}{12}=\dfrac{4}{3}\)
Bài 5:
a) \(x-\dfrac{6}{7}=\dfrac{5}{2}\)
\(x=\dfrac{5}{2}+\dfrac{6}{7}\)
\(x=\dfrac{47}{14}\)
b) \(\dfrac{12}{7}\div x+\dfrac{2}{3}=\dfrac{7}{5}\)
\(\dfrac{12}{7}\div x=\dfrac{7}{5}-\dfrac{2}{3}\)
\(\dfrac{12}{7}\div x=\dfrac{11}{15}\)
\(x=\dfrac{12}{7}\div\dfrac{11}{15}\)
\(x=\dfrac{180}{77}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(\dfrac{135}{2371}+\dfrac{24}{25}\right)\times\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)\)
\(=\left(\dfrac{135}{2371}+\dfrac{24}{25}\right)\times\left(\dfrac{3}{6}-\dfrac{2}{6}-\dfrac{1}{6}\right)\)
\(=\left(\dfrac{135}{2371}+\dfrac{24}{25}\right)\times0=0\)
đáp số : x = 2,4
giải thích các bước giải
\(\frac{x^2}{6}\)\(=\frac{24}{25}\)
Áp dụng tính chất hai phân số bằng nhau thì tích chéo của chúng bằng nhau
ta có : \(x^2\)\(.25=6.24\)
\(x^2\)\(.25=144\)
\(x^2\)\(=144:25=\frac{144}{25}\)\(=5,76\)
\(x^2\)\(=5,76=2,4^2\)
\(--->x=2,4\)
\(\frac{x^2}{6}=\frac{24}{25}\)
\(\Rightarrow x^2=\frac{24}{25}.6=\frac{144}{25}\)
\(\Rightarrow\orbr{\begin{cases}x^2=12^2\\x^2=\left(-12\right)^2\end{cases}}\Rightarrow\orbr{\begin{cases}x=12\\x=-12\end{cases}}\)