`-5/8xx5/12+5/8xx(-7/12)+17/8`

`=5/8xx(-5/12)+5/8xx(-7/12)+17/8`

`=5/8xx(-5/12-7/12)+17/8`

`=5/8xx(-12)/12+17/8`

`=5/8xx(-1)+17/8`

`=-5/8+17/8`

`=12/8=3/2`

\(-\dfrac{5}{8}\cdot\dfrac{5}{12}+\dfrac{5}{8}\cdot\left(-\dfrac{7}{12}\right)+\dfrac{17}{8}\)
\(=-\dfrac{5}{8}\cdot\dfrac{5}{12}+-\dfrac{5}{8}\cdot\dfrac{7}{12}+\dfrac{17}{8}\)
\(=-\dfrac{5}{8}\left(\dfrac{5}{12}+\dfrac{7}{12}\right)+\dfrac{17}{8}\)
\(=-\dfrac{5}{8}\cdot1+\dfrac{17}{8}\)
\(=-\dfrac{5}{8}+\dfrac{17}{8}\)
\(=\dfrac{12}{8}=\dfrac{3}{2}\)

Cảm ơn hai bn(⌒▽⌒)🥰🥰🥰

a) \(\left(-\frac{3}{5}\right)^{14}:\left(-\frac{3}{5}\right)^{13}\)

\(=\left(-\frac{3}{5}\right)^{14-13}\)

\(=\left(-\frac{3}{5}\right)^1\)

\(=-\frac{3}{5}.\)

Chúc bạn học tốt!

a) \(\left(\frac{-3}{5}\right)^{14}:\left(\frac{-3}{5}\right)^{13}=\frac{-3}{5}\)

a)

\(\left(-\frac{3}{5}\right)^{14}-\left(-\frac{3}{5}\right)^{13}\)

\(=\left(-\frac{3}{5}\right)^{14-13}\)

\(=\left(-\frac{3}{5}\right)^1=-\frac{3}{5}\)

b)

\(\left(-2\right)^3\cdot\left(\frac{3}{4}-0,25\right)\left(\frac{2}{\frac{1}{4}}-\frac{1}{\frac{1}{6}}\right)\)

\(=-8\cdot\left(\frac{3}{4}-\frac{1}{4}\right)\cdot\left(\frac{2}{4}-\frac{1}{6}\right)\)

\(=-\frac{8}{1}\cdot\frac{2}{4}\cdot\left(\frac{1}{2}-\frac{1}{6}\right)\)

\(=-\frac{16}{4}\cdot\left(\frac{3}{6}-\frac{1}{6}\right)\)

\(=-\frac{4}{1}\cdot\frac{2}{6}=-\frac{4}{1}\cdot\frac{1}{3}=-\frac{4}{3}\)

c)

\(\frac{7}{17}\cdot\frac{5}{8}-\frac{5}{8}\cdot\left(-\frac{3}{17}\right)-\frac{5}{8}\cdot\frac{18}{17}\)

\(=\frac{5}{8}\cdot\left[\frac{7}{17}-\left(-\frac{3}{17}\right)-\frac{18}{17}\right]\)

\(=\frac{5}{8}\cdot\left[\frac{7}{17}+\frac{3}{17}-\frac{18}{17}\right]\)

\(=\frac{5}{8}\cdot\left[\frac{7+3-18}{17}\right]\)

\(=\frac{5}{8}\cdot\left(-\frac{2}{17}\right)=\frac{5\cdot-2}{8\cdot17}=\frac{-10}{136}=\frac{-5}{68}\)

a, 720 : ( x - 17 ) = 12

=> x - 17 = 720 : 12 = 60

=> x = 60 + 17 = 77

\(a,\text{ }720\text{ : }\left(x-17\right)=12\)

                 \(\left(x-17\right)=720\text{ : }12\)

                  \(\left(x-17\right)=60\)

                                    \(x=60+17\)

                                    \(x=77\)

b, 26 + 8x = 6x + 46

=> 8x - 6x = 46 - 26

=> 2x = 20

=>x = 20: 2 =10

\(a,3\left(x-6\right)-11=22\)

\(\Rightarrow3\left(x-6\right)=22+11=33\)

\(\Rightarrow x-6=33:3=11\)

\(\Rightarrow x=11+6=17\)

\(b,4x-10-10=20\)

\(\Rightarrow4x=20+10+10=40\)

\(\Rightarrow x=40:4=10\)

\(c,5\left(x+2\right)+8=23\)

\(\Rightarrow5\left(x+2\right)=23-8=15\)

\(\Rightarrow x+2=15:5=3\)

\(\Rightarrow x=3-2=1\)

Đặt \(A=x^{13}-\left(8x^{12}-8x^{11}+8x^{10}-8x^9+.....+8x^2-8x^1\right)+8\)

Đặt \(B=8x^{12}-8x^{11}+8x^{10}-....+8x^2-8x^1\)

\(B=8.\left(x^{12}-x^{11}+x^{10}-x^9+....+x^2-x^1\right)\)

Đặt \(C=x^{12}-x^{11}+x^{10}-x^9+...+x^2-x\)

Suy ra \(C.x=x^{13}-x^{12}+x^{11}-x^{10}+.....+x^3-x^2\)

Nên \(C.x-C=x^{13}-x\)hay \(C.\left(x-1\right)=x^{13}-x\)

Khi đó \(C=\frac{x^{13}-x}{x-1}\)nên\(B=8.\frac{x^{13}-x}{x-1}\)

Từ đó tính tương tự nha , cách làm thì có thể sai những em vẫn cố gắng giúp , ai có cách hay hơn thì giải nhé 

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