Tính nhanh:
a)M \(=\dfrac{1234}{3702}+\dfrac{123123}{369369}+\dfrac{45}{135}-\dfrac{2234}{4468}\);
b)Q =\(\dfrac{456x123+333}{456x124-123}\)
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a: \(=\dfrac{-2}{12}-\dfrac{5}{12}+\dfrac{7}{12}=0\)
b: \(=\left(\dfrac{4}{45}-\dfrac{1}{45}+\dfrac{7}{45}+\dfrac{4}{45}-\dfrac{2}{45}-\dfrac{9}{45}\right)=\dfrac{3}{45}=\dfrac{1}{15}\)
a, bạn tự làm
b, \(B=\dfrac{5^2}{5}\left(1-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}+...+\dfrac{1}{101}-\dfrac{1}{106}\right)\)
\(=5\left(1-\dfrac{1}{106}\right)=\dfrac{5.105}{106}=\dfrac{525}{106}\)
c, đk : \(x\ne\dfrac{2}{3}\)
Ta có : \(\left|x-1\right|=2\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)(tm)
Với x = 3 suy ra \(C=\dfrac{2.9+9-1}{3.3-2}=\dfrac{26}{7}\)
Với x = -1 suy ra \(C=\dfrac{2-3-1}{-3-2}=\dfrac{-2}{-5}=\dfrac{2}{5}\)
\(-\dfrac{x}{27}-1=\dfrac{2}{3}\)
\(\Rightarrow-\dfrac{x}{27}=\dfrac{2}{3}+1=\dfrac{5}{3}\)
\(\Rightarrow-3x=27.5\)
\(\Rightarrow x=-135:\left(-3\right)\)
\(\Rightarrow x=-45\)
`->B`
Sửa đề: \(\left(\dfrac{1}{3}+\dfrac{3}{4}-\dfrac{13}{12}\right):\left(\dfrac{12}{23}+\dfrac{123}{234}+\dfrac{1234}{2345}\right)\)
\(=\left(\dfrac{4+9-13}{12}\right):\left(\dfrac{12}{23}+\dfrac{123}{234}+\dfrac{1234}{2345}\right)\)
=0
= \(\dfrac{5}{2}(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{2019}-\dfrac{1}{2021})\)
= \(\dfrac{5}{2}\left(1-\dfrac{1}{101}\right)\)
= \(\dfrac{5}{2}.\dfrac{100}{101}\)
= \(\dfrac{250}{101}\)
Ko bt
như con cặc