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24 tháng 1 2017

a) 

\(=-\frac{1}{2187}.2187\)

\(=-1\)

b) 

\(=\frac{1}{512}.512\)

\(=1\)

c) 

\(=\frac{8100}{225}=36\)

d) \(=10000\)

24 tháng 1 2017

a, \(\left(\frac{-1}{3}\right)^7.3^7=-\frac{1}{2187}.2187=-1\)

b, \(\left(0,125\right)^3.512=\frac{1}{512}.512\)

                                  \(=1\)

c, \(\frac{90^2}{15^2}=\frac{8100}{225}\)

              \(=8100:225=36\)

d, \(\frac{790^4}{79^4}=\left(790:79\right)^4\)

                 \(=10^4=10000\)

8 tháng 9 2021

toi ko co the bt day nh vau ko dau

17 tháng 3 2020

Bài 2:

a) \(\frac{8^{14}}{4^{12}}\)

\(=\frac{\left(2^3\right)^{14}}{\left(2^2\right)^{12}}\)

\(=\frac{2^{42}}{2^{24}}\)

\(=2^{18}\)

\(=262144.\)

b) \(\left(-\frac{1}{3}\right)^7.3^7\)

\(=\left[\left(-\frac{1}{3}\right).3\right]^7\)

\(=\left(-1\right)^7\)

\(=-1.\)

c) \(\frac{90^2}{15^2}\)

\(=\left(\frac{90}{15}\right)^2\)

\(=6^2\)

\(=36.\)

d) \(\frac{790^4}{79^4}\)

\(=\left(\frac{790}{79}\right)^4\)

\(=10^4\)

\(=10000.\)

Chúc bạn học tốt!

4 tháng 4 2020

Mk làm tiếp cho bạn Vũ Minh Tuấn nhé!

Bài 1:

\(-\frac{64}{343}=x^3\)

\(\Rightarrow x^3=\left(-\frac{4}{7}\right)^3\)

\(\Rightarrow x=-\frac{4}{7}\)

Vậy \(x=-\frac{4}{7}\)

\(\left(x+20\right)^{100}+\left|y+4\right|=0\)

Ta có: \(\left(x+20\right)^{100}\ge0;\left|y+4\right|\ge0\)

\(\Rightarrow\left\{{}\begin{matrix}\left(x+20\right)^{100}=0\\\left|y+4\right|=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=-20\\y=-4\end{matrix}\right.\)

Vậy \(x=-20;y=-4\)

\(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)

\(\Rightarrow\left(x-\frac{1}{2}\right)^3=\left(\frac{1}{3}\right)^3\)

\(\Rightarrow x-\frac{1}{2}=\frac{1}{3}\)

\(\Rightarrow x=\frac{5}{6}\)

Vậy \(x=\frac{5}{6}\)

\(\left(x+\frac{1}{2}\right)^2=\frac{4}{25}\)

\(\Rightarrow\left(x+\frac{1}{2}\right)^2=\left(\frac{2}{5}\right)^2\)

\(\Rightarrow\left[{}\begin{matrix}x+\frac{1}{2}=\frac{2}{5}\\x+\frac{1}{2}=-\frac{2}{5}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\frac{1}{10}\\x=-\frac{9}{10}\end{matrix}\right.\)

Vậy \(x\in\left\{-\frac{1}{10};-\frac{9}{10}\right\}\)

27 tháng 8 2017

 1)=133\18

2)=171\5

3)=9\7

4)=431\160

27 tháng 8 2017

ban tra loi ki cho mk nhe

12 tháng 8 2018

a) (1 / 7.7) 7 = 1

b) (0,125.8)3=1

c)( 0,25.0,25.32)2=22=4

d) (90/15) 3 = 6 3

) ( 790/79)4=104

f) (3/0,75)2=82

16 tháng 12 2017

Ta có dựa vào dãy tỉ số bằng nhau

1)\(\dfrac{x}{-5}=\dfrac{y}{2}=\dfrac{x-y}{-5-2}=1\)

suy ra x=-5 , y=2

16 tháng 12 2017

2) bạ tự làm nhé

3)=\(\dfrac{-1}{3^7}.3^7=-1\)

b)=\(\dfrac{1}{512}.512=1\)

c)=\(\dfrac{90^2}{15^2}=2^2.3^2=36\)

d)=\(\dfrac{790^4}{79^4}=10^4=10000\)

Tick em nha

HQ
Hà Quang Minh
Giáo viên
19 tháng 9 2023

a)

\(\begin{array}{l}0,75 - \frac{5}{6} + 1\frac{1}{2} = \frac{3}{4} - \frac{5}{6} + \frac{3}{2}\\ = \frac{9}{{12}} - \frac{{10}}{{12}} + \frac{{18}}{{12}} = \frac{{17}}{{12}}\end{array}\)                                    

b)

\(\begin{array}{l}\frac{3}{7} + \frac{4}{{15}} + \left( {\frac{{ - 8}}{{21}}} \right) + \left( { - 0,4} \right) = \frac{3}{7} + \frac{4}{{15}} - \frac{8}{{21}} - \frac{2}{5}\\ = \left( {\frac{3}{7} - \frac{8}{{21}}} \right) + \left( {\frac{4}{{15}} - \frac{2}{5}} \right)\\ = \left( {\frac{9}{{21}} - \frac{8}{{21}}} \right) + \left( {\frac{4}{{15}} - \frac{6}{{15}}} \right)\\ = \frac{1}{{21}} + \left( {\frac{{ - 2}}{{15}}} \right)\\ = \frac{5}{{105}} - \frac{{14}}{{105}}\\ = \frac{{ - 9}}{{105}} = \frac{{ - 3}}{{35}}\end{array}\)

c)

\(\begin{array}{l}0,625 + \left( {\frac{{ - 2}}{7}} \right) + \frac{3}{8} + \left( {\frac{{ - 5}}{7}} \right) + 1\frac{2}{3}\\ = \frac{5}{8} + \left( {\frac{{ - 2}}{7}} \right) + \frac{3}{8} - \frac{5}{7} + \frac{5}{3}\\ = \left( {\frac{5}{8} + \frac{3}{8}} \right) + \left( {\frac{{ - 2}}{7} - \frac{5}{7}} \right) + \frac{5}{3}\\ = 1 - 1 + \frac{5}{3} = \frac{5}{3}\end{array}\)          

 d)

\(\begin{array}{l}\left( { - 3} \right).\left( {\frac{{ - 38}}{{21}}} \right).\left( {\frac{{ - 7}}{6}} \right).\left( { - \frac{3}{{19}}} \right)\\ = \frac{{ - 3.\left( { - 38} \right).\left( { - 7} \right).\left( { - 3} \right)}}{{21.6.19}}\\ = \frac{{3.38.7.3}}{{21.6.19}}\\ = \frac{{3.2.19.7.3}}{{3.7.3.2.19}}\\ = 1\end{array}\)

e)

 \(\begin{array}{l}\left( {\frac{{11}}{{18}}:\frac{{22}}{9}} \right).\frac{8}{5} = \left( {\frac{{11}}{{18}}.\frac{9}{{22}}} \right).\frac{8}{5}\\ = \frac{{11.9.4.2}}{{9.2.2.11.5}} = \frac{2}{5}\end{array}\)                                   

 g)

\(\left[ {\left( {\frac{{ - 4}}{5}} \right).\frac{5}{8}} \right]:\left( {\frac{{ - 25}}{{12}}} \right) = \frac{{ - 20}}{{40}}:\left( {\frac{{ - 25}}{{12}}} \right)\\ = \frac{{ - 1}}{2}.\frac{{ - 12}}{{25}} = \frac{6}{{25}}\)

8 tháng 7 2015

a) \(\frac{790^4}{79^4}=\frac{79^4.10^4}{79^4}=10^4=10000\)

b) \(\frac{3^2}{0,375^2}=\frac{0,375^2.8^2}{0,375^2}=8^2=64\)

c) \(3^2.\frac{1}{243}.81^2.\frac{1}{3^3}=3^2.3^{-5}.3^8.3^{-3}=3^2=9\)

d) \(\left(4.2^5\right):\left(2^3.\frac{1}{16}\right)=2^7:\left(2^3.2^{-4}\right)=2^7:2^{-1}=2^7:\frac{1}{2}=2^8\)