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a) =-5/7 +7/8-2/7+1/8- -1/12+ -13/12
=(-5/7-2/7)+(7/8+1/8)-(-1/12--13/12)
=-7/7+8/8 - 12/12
= -1+1+1
=1
b)= ( -3/8+11/8)-(12/11+ -1/11)+(-3/5- 2/5)
= 1- 1 + (-1)
=-1
1/4+2/5+6/8+2/15+6/7
=(1/4+6/8)+(2/5+2/15)+6/7
=(2/8+6/8)+(6/15+2/15)+6/7
=1+8/15+6/7
=1+56/105+90/105
=1+146/105
=1+105/105+41/105
=1+1+41/105
=2+41/105
=2 và 41/105
2 và 41/105 là hỗn số nha
1/4+2/5+6/8+2/15+6/7
Ta có:
1/4=1-3/4
6/8=3/4
2/15=2/3*5=1/3-1/5
==> 1-3/4+2/5+3/4+1/3-1/5+6/7
=1+1/3+1/5+6/7
=(105+35+21+90)/105
=251/105.
\(4\frac{3}{4}+\left(-0,37\right)+\frac{1}{8}+\left(-1,28\right)+\left(-2,5\right)+3\frac{1}{12}\)
\(=\frac{19}{4}+-\frac{37}{100}+\frac{1}{8}+-\frac{128}{100}+-\frac{250}{100}+\frac{37}{12}\)
\(=\left(\frac{19}{4}+\frac{1}{8}+\frac{37}{12}\right)-\left(\frac{37}{100}+\frac{128}{100}+\frac{250}{100}\right)\)
\(=\left(\frac{114}{24}+\frac{3}{24}+\frac{74}{24}\right)-\frac{415}{100}\)
\(=\frac{191}{24}-\frac{415}{100}\)
\(=\frac{457}{120}\)
Tham khảo nha !!!
\(4\frac{3}{4}+\left(-0,37\right)+\frac{1}{8}+\left(-1,28\right)+\left(-2,5\right)+3\frac{1}{12}\)
\(=\frac{19}{4}+\frac{-37}{100}+\frac{1}{8}+\frac{-32}{25}+\frac{-5}{2}+\frac{37}{12}\)
\(=\left(\frac{19}{4}+\frac{1}{8}+\frac{-5}{2}\right)+\left(\frac{-37}{100}+\frac{-32}{25}\right)+\frac{37}{12}\)
\(=\frac{19}{8}+\frac{-33}{20}+\frac{37}{12}\)
\(=\frac{29}{40}+\frac{37}{12}\)
\(=\frac{457}{120}\)
\(a)\frac{x}{4}-\frac{3}{7}+\frac{2}{5}=\frac{31}{140}\)
\(\Leftrightarrow\frac{x}{4}-\frac{1}{35}=\frac{31}{140}\)
\(\Leftrightarrow\frac{x}{4}=\frac{1}{4}\Leftrightarrow x=1\)
\(b)\frac{5}{12}+\frac{5}{x}-\frac{1}{8}=\frac{1}{12}\)
\(\Leftrightarrow\frac{5}{x}+\frac{7}{24}=\frac{1}{12}\)
\(\Leftrightarrow\frac{5}{x}=-\frac{5}{24}\Leftrightarrow x=-24\)
a) Chữ số tận cùng của \(234^{5^{6^7}}\)là 6
do \(234^5\)có tận cùng là 4 (mũ lẻ)
\(234^{5^6}\)có tận cùng là 6 (mũ chẵn)
=> \(234^{5^{6^7}}\)có tận cùng là 6
<=> |x+2| = 13
<=> \(\orbr{\begin{cases}x+2=13\\x+2=-13\end{cases}\Rightarrow}\orbr{\begin{cases}x=11\\x=-15\end{cases}}\)
Vậy.........
hok tốt
..........
\(|x+2|=12+\left(-3\right)+\left|-4\right|\)
\(|x+2|=12-3+4\)
\(\left|x+2\right|=13\)
\(\Rightarrow x\in\left\{-15;11\right\}\)
\(\frac{4^8.3^{12}.27^2}{6^{12}.9^3}\)
= \(\frac{\left(2^2\right)^8.3^{12}.27^2}{\left(2.3\right)^{12}.\left(3^2\right)^3}\)
= \(\frac{2^{16}.3^{12}.27^2}{2^{12}.3^{12}.27^2}\)
= \(\frac{2^{16}}{2^{12}}\)= 24 = 16
TA CÓ : \(3+3^3+3^5+3^7+...+3^{31}\)= \(\left(3+3^3\right)+\left(3^5+3^7\right)+...+\left(3^{29}+3^{31}\right)\)
=\(\left(3+3^3\right)+3^4\left(3+3^3\right)+3^8\left(3+3^3\right)+...+3^{28}\left(3+3^3\right)\) = \(30+30\cdot3^4+...+30\cdot3^{28}⋮30\)
CHO MÌNH XIN K NẾU BẠN THẤY ĐÚNG
\(\frac{-5}{8}\) \(-\) \(\frac{7}{-12}\)
=\(\frac{-5}{8}-\frac{-7}{12}\) =\(\frac{-30}{48}-\frac{-28}{48}\)
=\(\frac{-2}{48}=\frac{-1}{24}\)
Tính:
\(-\frac58\) - \(\frac{7}{-12}\)
= \(-\frac{15}{24}\) + \(\frac{14}{24}\)
= - \(\frac{1}{24}\)