Question

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Answer 1

Bài 1:

a: \(\left(-1,25\right)\cdot\dfrac{17}{21}\cdot\left(-0,8\right)\cdot\dfrac{7}{34}\)

\(=\left(-1,25\right)\cdot\left(-0,8\right)\cdot\dfrac{17}{34}\cdot\dfrac{7}{21}\)

\(=1\cdot\dfrac{1}{2}\cdot\dfrac{1}{3}=\dfrac{1}{6}\)

b: \(2\dfrac{3}{4}\cdot\dfrac{-1}{5}+2\dfrac{3}{4}\cdot\dfrac{6}{5}=2\dfrac{3}{4}\left(-\dfrac{1}{5}+\dfrac{6}{5}\right)=\dfrac{11}{4}\cdot1=\dfrac{11}{4}\)

c: \(\dfrac{7}{18}\cdot\dfrac{-15}{19}+\dfrac{21}{9}\cdot\dfrac{-7}{18}=-\dfrac{7}{18}\left(\dfrac{15}{19}-\dfrac{21}{9}\right)\)

\(=-\dfrac{7}{18}\cdot\dfrac{-264}{171}=\dfrac{308}{513}\)

d: \(\left(-\dfrac{3}{4}+\dfrac{2}{5}\right):\dfrac{7}{3}+\left(\dfrac{3}{5}+\dfrac{-1}{4}\right):\dfrac{7}{3}\)

\(=\left(-\dfrac{3}{4}+\dfrac{2}{5}+\dfrac{3}{5}-\dfrac{1}{4}\right):\dfrac{7}{3}\)

\(=\left(-1+1\right)\cdot\dfrac{3}{7}=0\)

e: \(\left(-0,75\right)\cdot\dfrac{18}{25}\cdot\dfrac{50}{54}=-\dfrac{3}{4}\cdot\dfrac{18}{54}\cdot\dfrac{50}{25}=-\dfrac{3}{4}\cdot\dfrac{1}{3}\cdot2=-\dfrac{2}{4}=-\dfrac{1}{2}\)

g: \(\left(\dfrac{1}{2}+2\dfrac{1}{6}-\dfrac{1}{3}\right):\left(5-\dfrac{1}{2}-\dfrac{1}{3}\right)\)

\(=\left(\dfrac{1}{2}+\dfrac{13}{6}-\dfrac{1}{3}\right):\left(\dfrac{30}{6}-\dfrac{3}{6}-\dfrac{2}{6}\right)\)

\(=\dfrac{14}{6}:\dfrac{25}{6}=\dfrac{14}{25}\)

Bài 2:

a: \(\left(-\dfrac{2}{3}\right)^3=\dfrac{\left(-2\right)^3}{3^3}=-\dfrac{8}{27}\)

\(\left(-\dfrac{3}{5}\right)^2=\dfrac{\left(-3\right)^2}{5^2}=\dfrac{9}{25}\)

\(\left(-0,2\right)^3=\left(-\dfrac{1}{5}\right)^3=\dfrac{\left(-1\right)^3}{5^3}=-\dfrac{1}{125}\)

\(\left(-0,5\right)^2=0,5\cdot0,5=0,25\)

\(\left(37,5\right)^0=1\)

b: \(\left(-0,25\right)^7:\left(-0,25\right)^5=\left(-0,25\right)^{7-5}=\left(-0,25\right)^2=\dfrac{1}{16}\)

c: \(\left(\dfrac{5}{3}\right)^{10}\cdot\left(\dfrac{3}{5}\right)^{10}=\left(\dfrac{5}{3}\cdot\dfrac{3}{5}\right)^{10}=1^{10}=1\)

d: \(\left(\dfrac{25}{81}\right)^4:\left(\dfrac{5}{9}\right)^7=\left(\dfrac{5^2}{9^2}\right)^4:\left(\dfrac{5}{9}\right)^7\)

\(=\left(\dfrac{5}{9}\right)^8:\left(\dfrac{5}{9}\right)^7=\dfrac{5}{9}\)

e: \(\left[\left(\dfrac{3}{7}\right)^4\cdot\left(\dfrac{3}{7}\right)^5\right]:\left(\dfrac{3}{7}\right)^7=\left(\dfrac{3}{7}\right)^{4+5-7}=\left(\dfrac{3}{7}\right)^2=\dfrac{9}{49}\)

f: \(\left(-\dfrac{8}{7}\right)^2:\left(-\dfrac{8}{7}\right)^2=\left(-\dfrac{8}{7}\right)^{2-2}=\left(-\dfrac{8}{7}\right)^0=1\)