thục hiện phép tính
3.(-5)^+2.(-15)-20
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\(\left(-216\right):9+7^5:7^3-\left(-4\right)^2.5\)
\(\Leftrightarrow\left(-24\right)+7^2-16\)
\(\Leftrightarrow\left(-24\right)+49-16\)
\(\Leftrightarrow25-16\)
\(\Leftrightarrow9\)
\(3.\left(-5\right)^2+2.\left(-15\right)-20=3.25-2.15-20=75-30-20=25\)
bai 1
20:(24-(3^2.4-34)^2)-20
=20:(24-(9.4-34)^2)-20
=20:(24-2^2)-20
=20:20-20
=-19
bai 2
a
14+5x=4^6:4^3
14+5x=4^3
14+5x=64
5x=64-14
5x=50
x=50:5
x=10
b
189-2.(93-x)=59
2..(93-x)=189-59
2.(93-x)=130
(93-x)=130:2
93-x=65
x=93-65
x=28
1) \(20:\left[24-\left(3^2.4-34\right)^2\right]-20\)
\(=20:\left[24-\left(9.4-34\right)^2\right]-20\)
\(=20:\left[24-4\right]-20\)
\(=20:20-20\)
\(=1-20\)
\(=-19\)
2)a.\(14+5x=4^6:4^3\)
\(14+5x=64\)
\(5x=64-14\)
\(5x=50\)
\(\Rightarrow x=10\)
b) 189-2(93-x)=59
2(93-x) =189-59
2(93-x) =130
93-x =130:2
93-x =65
x =93-65
x =28
Học tốt nha!!!
\(\dfrac{5}{12}+\dfrac{-7}{12}=\dfrac{-2}{12}=\dfrac{-1}{6}\)
\(\dfrac{1}{2}+\dfrac{-2}{3}=\dfrac{3}{6}+\dfrac{-4}{6}=\dfrac{-1}{6}\)
\(\dfrac{3}{5}-\dfrac{4}{3}=\dfrac{9}{15}-\dfrac{20}{15}=\dfrac{-11}{15}\)
\(\dfrac{-15}{14}.\dfrac{21}{20}=\dfrac{-315}{280}=\dfrac{-9}{8}\)
\(\dfrac{-1}{6}\)
\(\dfrac{-1}{6}\)
\(\dfrac{-11}{15}\)
\(\dfrac{-9}{8}\)
a, (\(\dfrac{9}{10}\) - \(\dfrac{15}{16}\)) \(\times\) ( \(\dfrac{5}{12}\) - \(\dfrac{11}{15}\) - \(\dfrac{7}{20}\))
= (\(\dfrac{72}{80}\) - \(\dfrac{75}{80}\)) \(\times\) (\(\)\(\dfrac{25}{60}\) - \(\dfrac{44}{60}\) - \(\dfrac{21}{60}\))
= - \(\dfrac{3}{80}\) \(\times\) (- \(\dfrac{2}{3}\))
= \(\dfrac{1}{40}\)
b, (-1)3 + (- \(\dfrac{2}{3}\))2 : 2\(\dfrac{2}{3}\) + \(\dfrac{5}{6}\)
= -13 + \(\dfrac{4}{9}\) : \(\dfrac{8}{3}\) + \(\dfrac{5}{6}\)
= -1 + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{3}{8}\) + \(\dfrac{5}{6}\)
= -1 + \(\dfrac{1}{6}\) + \(\dfrac{5}{6}\)
= -1 + 1
= 0
=\(\left[\dfrac{\left(0,4.2\right)^5}{\left(0,4\right)^6}+\dfrac{2^9.2^6.3^8}{\left(3.2\right)^6.2^9}\right]=\left[\dfrac{\left(0,4\right)^5.2^5}{\left(0,4\right)^6}+\dfrac{2^6.3^8}{3^6.2^6}\right]\)
=\(\left[\dfrac{2^5}{0,4}+3^2\right]\)
=\(\left[80+9\right]=89\)
\(\left[\dfrac{\left(2.0,4\right)^5}{0,4,0,4^5}+\dfrac{2^{15}.3^8}{3^6.2^6.2^9}\right]\div\dfrac{3^{20}.5^{30}}{3^{15}.5^{30}}\)
\(=\left[\dfrac{2^5.0.4^5}{0,4.0,4^5}+\dfrac{2^{15}.3^8}{3^6.2^{15}}\right]\div3^5\)
\(=\left[\dfrac{2^5}{0,4}+3^2\right]\div243\)
\(=80+\left(3^5\div3^2\right)\)
\(=80+3^3\)
\(=80+27\)
\(=107\)
\(3.\left(-5\right)^2+2.\left(-15\right)-20=-15.\left(-5\right)+2.\left(-5\right).3+4.\left(-5\right)\)
\(=-5.\left(-15+2.3+4\right)\)
\(=-5.\left(-5\right)\)
\(=25\)