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\(a)\)
\(\frac{-25}{16}=\frac{\left(-5\right).5}{4.4}=\frac{\left(-5\right).5.3}{4.4.3}=\frac{\left(-5\right).15}{12.4}=\frac{\left(-5\right)}{12}.\frac{15}{4}\)
\(b)\)
\(\frac{-25}{16}=\frac{\left(-25\right).4.5}{16.4.5}=\frac{\left(-4\right).25.5}{5.16.4}=\frac{\left(-4\right)}{5}.\frac{125}{64}=\frac{\left(-4\right)}{5}:\frac{64}{125}\)
A=1+(2-3-3+5)+(6-7-8+9)+....+(98-99-100+101)+102
=1+0+0+....+102=103
b) |1-2x|>7
=> 1-2x>7 hoặc 1-2x<-7
=> 2x<-6 hoặc 2x>8
=> x<-3 hoặc x>4
3,
a) (−23+37):45+(−13+47):45
= \(-\frac{5}{21}:\frac{4}{5}+\frac{5}{21}:\frac{4}{5}\)
= \(\left(-\frac{5}{21}+\frac{5}{21}\right):\frac{4}{5}\)
= \(0:\frac{4}{5}=0\)
2,
a) \(\frac{-3}{4}\).\(\frac{12}{-5}\).(\(\frac{-25}{6}\))
= \(\frac{-3.4.3.\left(-5\right).5}{4.\left(-5\right).3.3}\)
= \(-5\)
b) (−2).\(\frac{-38}{21}\).\(\frac{-7}{4}\).(\(\frac{-3}{8}\))
= \(\frac{-2.\left(-38\right)\left(-7\right)\left(-3\right)}{\left(-7\right)\left(-3\right)\left(-2\right)\left(-2\right).8}\)
= \(\frac{19}{8}\)
c) (\(\frac{11}{12}:\frac{33}{16}\)).\(\frac{3}{5}\)
= \(\left(\frac{11}{12}.\frac{16}{33}\right).\frac{3}{5}\)
= \(\frac{4}{9}.\frac{3}{5}\)
= \(\frac{4}{15}\)
d) \(\frac{7}{23}\left[\left(\frac{-8}{6}\right)-\frac{45}{18}\right]\)
= \(\frac{7}{23}.\left(\frac{-41}{10}\right)\)
= \(\frac{-287}{203}\)
3. Tính:
a) (\(\frac{-2}{3}+\frac{3}{7}\)):\(\frac{4}{5}\)+(\(\frac{-1}{3}+\frac{4}{7}\)):\(\frac{4}{5}\)
= (\(\frac{-2}{3}+\frac{3}{7}\)\(+\)\(\frac{-1}{3}+\frac{4}{7}\)) : \(\frac{4}{5}\)
= 0 : \(\frac{4}{5}\)
= 0
b) \(\frac{5}{9}\):(\(\frac{1}{11}-\frac{5}{22}\))+\(\frac{5}{9}\):(\(\frac{1}{15}-\frac{2}{3}\))
= \(\frac{5}{9}\): \(\frac{-3}{22}\)+ \(\frac{5}{9}\): \(\frac{-3}{5}\)
= \(\frac{5}{9}\): \(\frac{-81}{110}\)
= \(\frac{-550}{729}\)
Giải
a) Ta có : \(\frac{-25}{16}=\frac{-5}{12}.\frac{15}{4}\)
b) Ta có : \(\frac{-25}{16}=\frac{-4}{5}.\frac{64}{125}\)
a) Gọi số cần tìm là: `x` \(\left(x\in Q;x\ne0\right)\)
Ta có: \(-\dfrac{25}{16}=\dfrac{-5}{12}x\)
`=>` \(x=-\dfrac{25}{16}\div\dfrac{-5}{12}=\dfrac{15}{4}\)
Vậy \(-\dfrac{25}{16}=\dfrac{15}{4}.\dfrac{-5}{12}\).
b) Gọi số cần tìm là: \(y\) \(\left(y\in Q;y\ne0\right)\)
Ta có: \(-\dfrac{25}{16}=-\dfrac{4}{5}\div y\)
\(\Rightarrow y=-\dfrac{4}{5}\div\dfrac{-25}{16}=\dfrac{64}{125}\)
Vậy \(-\dfrac{25}{16}=-\dfrac{4}{5}\div\dfrac{64}{125}\).
a) Gọi số cần tìm là: x (x∈Q;x≠0)
Ta có: −2516=−512x
⇒
x=−2516÷−512=154
Vậy −2516=154.−512
.
b) Gọi số cần tìm là: y
(y∈Q;y≠0)
Ta có: −2516=−45÷y
⇒y=−45÷−2516=64125
Vậy −2516=−45÷64125
.
− 3 4 ⋅ 12 − 5 : − 25 16 = − 3 4 ⋅ 12 − 5 ⋅ − 16 25 = 9 5 . − 16 25 = − 144 125