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1.
a) \(\frac{-7}{9}.2\frac{3}{4}=\frac{-7}{9}.\frac{11}{4}=\frac{-77}{36}\)
b) \(\frac{2}{3}+\frac{1}{3}.\frac{-2}{5}=\frac{2}{3}+\frac{-2}{15}=\frac{8}{15}\)
c) \(\frac{3}{4}.15\frac{1}{3}-\frac{3}{4}.43\frac{1}{3}=\frac{3}{4}.\frac{46}{3}-\frac{3}{4}.\frac{130}{3}=\frac{23}{2}-\frac{65}{2}=-21\)
d) \(\left(-49,1\right).\frac{13}{27}-58,9.\frac{13}{27}=\frac{13}{27}.\left(-49,1-58,9\right)=\frac{13}{27}.\left(-108\right)=-52\)
e) \(0,375:\left(-4,5\right)=\frac{-1}{12}\)
f) \(3\frac{1}{7}:\left(-1\frac{3}{7}\right)=\frac{22}{7}:\frac{-10}{7}=\frac{-11}{5}\)
g) \(9\frac{1}{3}:4\frac{2}{3}-2=\frac{28}{3}:\frac{14}{3}-2=2-2=0\)
h) \(\left(7\frac{3}{4}:0,3125+4,5.2\frac{2}{45}\right):\left(-8,5\right)=\left(\frac{31}{4}:\frac{5}{16}+\frac{9}{2}.\frac{92}{45}\right):\frac{-17}{2}=\left(\frac{124}{5}+\frac{46}{5}\right):\frac{-17}{2}=34:\frac{-17}{2}=-4\)
Bài 1 : Tính:
a)
\(\frac{-7}{9}.2\frac{3}{4}=\frac{-7}{9}.\frac{11}{4}=\frac{-77}{36}\)
b)
\(\frac{2}{3}+\frac{1}{3}.\frac{-2}{5}=\frac{2}{3}+\frac{-2}{15}=\frac{10}{15}+\frac{-2}{15}=\frac{8}{15}\)
c)
\(\frac{3}{4}.15\frac{1}{3}-\frac{3}{4}.43\frac{1}{3}=\frac{3}{4}.\frac{46}{3}-\frac{3}{4}.\frac{130}{3}\)\(=\frac{23}{2}-\frac{65}{2}=\frac{-42}{2}=-21\)
....
Tự lm tiếp dạng như v
Bài 2 :
\(A=\frac{-6}{11}.\frac{7}{10}.\frac{11}{-6}.-20=\left(\frac{-6}{11}.\frac{11}{-6}\right).\left(\frac{7}{10}.-20\right)\)\(=1.\left(-14\right)=-14\)
.....
Bài 3 :
\(\frac{3}{7}.x-\frac{2}{5}.x=\frac{-17}{35}\)
\(\Leftrightarrow\frac{3}{7}-\frac{2}{5}.x=\frac{-17}{35}\)
\(\Leftrightarrow\frac{1}{35}x=\frac{-17}{35}\)
\(\Leftrightarrow x=\frac{-17}{35}:\frac{1}{35}\)
\(\Leftrightarrow x=\frac{-17}{35}.35=-17\)
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Viết sai đề rùi nha bn
Đề đây, mk giải lun
(x-1)/13-(2x-13)/15=(3x-15)/27-(4x-27)/29
<=>15(x-1)/195-13(2x-13)/195=3(x-5)/27-4x-27/29
<=>15x-15-26x+169/195=29(x-5)/261-9(4x-27)/261
<=>-11+154/195=29x-145-36x+243/261
<=>-11x+154/195=-7x+98/261
<=>(11x+154)261=195(7x+98)
<=>2871x=-21084
<=>x=-14
Vậy x= -14
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(-27\right)^{27}=\left(-3\right)^{3^{27}}=\left(-3\right)^{81}\)
\(\left(-243\right)^{13}=\left(-3\right)^{5^{13}}=\left(-3\right)^{65}\)
\(\Rightarrow\left(-27\right)^{27}< \left(-243^{13}\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{27^{10}+9^5}{9^{13}+27^2}\)
\(=\dfrac{\left(3^3\right)^{10}+\left(3^2\right)^5}{\left(3^2\right)^{13}+\left(3^3\right)^2}\)
\(=\dfrac{3^{30}+3^{10}}{3^{26}+3^6}\)
\(=\dfrac{3^{10}\cdot\left(3^{20}+1\right)}{3^6\cdot\left(3^{20}+1\right)}\)
\(=\dfrac{3^{10}}{3^6}\)
\(=3^{10-6}\)
\(=3^4\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\dfrac{27^{10}+9^5}{9^{13}+27^2}\\ =\dfrac{\left(3^3\right)^{10}+\left(3^2\right)^5}{\left(3^2\right)^{13}+\left(3^3\right)^2}\\ =\dfrac{3^{30}+3^{10}}{3^{26}+3^6}\\ =\dfrac{3^{10}\left(3^{20}+1\right)}{3^6\left(3^{20}+1\right)}\\ =\dfrac{3^{10}}{3^6}\\=3^4\\ =81\)
\(A=\dfrac{27^{10}+9^5}{9^{13}+27^2}\)
\(A=\dfrac{\left(3^3\right)^{10}+\left(3^2\right)^5}{\left(3^2\right)^{13}+\left(3^3\right)^2}\)
\(A=\dfrac{3^{30}+3^{10}}{3^{26}+3^6}\)
\(A=\dfrac{3^{10}+\left(3^{20}+1\right)}{3^6.\left(3^{20}+1\right)}\)
\(A=\dfrac{3^{10}}{3^6}\)
\(A=3^4\)
\(A=81\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giải
\(\left(-27\right)^{27}=\left(-3^3\right)^{27}=\left(-3\right)^{81}\)
\(\left(-243\right)^{13}=\left(-3^5\right)^{13}=\left(-3\right)^{63}\)
=>\(\left(-27\right)^{27}>\left(-243\right)^{13}\)
Bạn học tốt!^^
\(\left(-3^5\right)^{13}=\left(-3\right)^{65}\) nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\Leftrightarrow2^x=\dfrac{2^{30}\cdot5^7+2^{13}\cdot5^{27}}{2^{27}\cdot5^7+2^{10}\cdot5^{27}}\)
\(\Leftrightarrow2^x=\dfrac{2^{13}\cdot5^7\left(2^{17}+5^{20}\right)}{2^{10}\cdot5^7\left(2^{17}+5^{20}\right)}=2^3\)
=>x=3
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