bài 1
a] 1- (2/5+1/10) b)5/8 : 1/2
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`#3107.101107`
1.
`a,`
`2 - 2/3 + 2,5 + 1/3 + 3 + 1/2`
`= (2 + 2,5 + 3) - (2/3 - 1/3 - 1/2)`
`= 7,5 - (-1/6)`
`= 7,5 + 1/6`
`= 23/3`
`b,`
`9/10 - (6/5 * 3/2 + 7/4)`
`= 9/10 - (18/10 + 7/4)`
`= 9/10 - 18/10 - 7/4`
`= -9/10 - 7/4`
`= -53/20`
Bài 2:
a) Ta có: \(f\left(2\right)-f\left(-1\right)=7\)
\(\Leftrightarrow2\left(m-1\right)-\left(-1\right)\cdot\left(m-1\right)=7\)
\(\Leftrightarrow2m-2+m-1=7\)
\(\Leftrightarrow3m-3=7\)
\(\Leftrightarrow3m=10\)
hay \(m=\dfrac{10}{3}\)
a: =-1/2+2/3=-3/6+4/6=1/6
b: =-15/20-16/20=-31/20
c: =-5/9+5/12=-60/108+45/108=-15/108=-5/36
\(a.\dfrac{1}{-2}=\dfrac{-1}{2}\)
\(\dfrac{-3}{6}+\dfrac{4}{6}=\dfrac{1}{6}\)
\(b.\dfrac{-15}{20}-\dfrac{16}{20}=\dfrac{-31}{20}\)
\(c.\dfrac{-5}{9}+\dfrac{5}{12}=\dfrac{-60}{108}+\dfrac{45}{108}=\dfrac{-15}{108}\)
a) ĐKXĐ: \(x\ge-\dfrac{1}{2}\)
b) ĐKXĐ: \(\left[{}\begin{matrix}x\ge2\\x\le-2\end{matrix}\right.\)
c) ĐKXĐ: \(x>-\dfrac{5}{3}\)
d) ĐKXĐ: \(3\le x\le10\)
e) ĐKXĐ: \(\left\{{}\begin{matrix}x>-4\\x\ne4\end{matrix}\right.\)
a.-1,75-(-\(\dfrac{1}{9}\)-2\(\dfrac{1}{8}\))
-1,75-\(\dfrac{1}{9}+\dfrac{17}{8}\)
\(-\dfrac{7}{4}-\dfrac{1}{9}+\dfrac{17}{8}\)
\(\dfrac{-126}{72}-\dfrac{8}{72}+\dfrac{153}{72}\)
=\(\dfrac{19}{72}\)
b.\(\dfrac{-1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\left(\dfrac{21}{8}-\dfrac{1}{3}\right)\)
\(\dfrac{-1}{12}-\dfrac{21}{8}+\dfrac{1}{3}\)
\(\dfrac{-2}{24}-\dfrac{63}{24}+\dfrac{64}{24}\)
=\(\dfrac{-1}{24}\)
Dấu "^" của cậu nghĩa là phân số?
\(a,-1,75-\left(-\dfrac{1}{9}-2\dfrac{1}{18}\right)=-\dfrac{7}{4}-\left(-\dfrac{2}{18}-\dfrac{37}{18}\right)=-\dfrac{7}{4}+\dfrac{13}{6}=\dfrac{5}{12}\)
\(b,-\dfrac{1}{12}-\left(2\dfrac{5}{8}-\dfrac{1}{3}\right)=-\dfrac{1}{12}-\dfrac{55}{24}=-\dfrac{19}{8}\)
\(c,-\dfrac{5}{6}-\left(-\dfrac{3}{8}+\dfrac{1}{30}\right)=-\dfrac{5}{6}+\dfrac{41}{120}=-\dfrac{59}{120}\)
\(a,1-\left(\frac{2}{5}+\frac{1}{10}\right)\)
\(=1-\left(\frac{4}{10}+\frac{1}{10}\right)\)
\(=1-\frac{5}{10}\)
\(=1-\frac{1}{2}\)
\(=\frac{1}{2}\)
\(b,\frac{5}{8}\div\frac{1}{2}\)
\(=\frac{5}{8}\times\frac{2}{1}\)
\(=\frac{10}{8}\)
\(=\frac{5}{4}\)
\(1-\left(\frac{2}{5}+\frac{1}{10}\right)\)
\(=1-\left(\frac{4}{10}+\frac{1}{10}\right)\)
\(=1-\frac{5}{10}\)
\(=1-\frac{1}{2}\)
\(=\frac{1}{2}\)
\(\frac{5}{8}:\frac{1}{2}\)
\(=\frac{5}{8}\cdot\frac{2}{1}\)
\(=\frac{5}{4}\)