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6:=(3/2)*(3/2)^2*(3/2)^4=(3/2)^7
7: =(1/2)^7*2^3*2^5*2^8=2^9
8: =(-1/7)^4*5^4=(-5/7)^4
9: =2^2*2^5:(2^3/2^4)
=2^7/2=2^6
10: =(1/7)^3*7^2=1/7
bài 1
a. = -10/3
b. = 14/5
c = 1/9
p = 1/9
bài 2.
a. x= 271/75
b. x = 1/3
bài 2
a. x - 10/3 = 7/15 . 3/5
x - 10/3 = 7/25
x = 7/25 + 10/3
x = 271/75
b. 8/23 . 46/24 - x = 1/3
2/3 - x = 1/3
x = 2/3 - 1/3
x = 1/3
\(x-1\in\left\{1;6;2;3;-1;-6;-2;-3\right\}\)
\(\Leftrightarrow x\in\left\{2;7;3;4;0;-5;-1;-2\right\}\)
làm lại
ta có : \(\frac{1}{10}+\frac{1}{40}+\frac{1}{88}+...+\frac{1}{\left(x+2\right)\left(x+5\right)}=\frac{3}{20}\)
=>\(\frac{1}{2.5}+\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{\left(x+2\right)\left(x+5\right)}=\frac{3}{20}\)
=>\(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+....+\frac{3}{\left(x+2\right)\left(x+5\right)}=\frac{9}{20}\)
=>\(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{x+2}-\frac{1}{x+5}=\frac{9}{20}\)
=>\(\frac{1}{2}-\frac{1}{x+5}=\frac{9}{20}\)
=>\(\frac{1}{x+5}=\frac{1}{2}-\frac{9}{20}\)
=>\(\frac{1}{x+5}=\frac{1}{20}\)
=>\(x+5=20\)
=>\(x=20-5\)
=>\(x=15\)
ta có : \(\frac{1}{10}+\frac{1}{40}+\frac{1}{88}+....+\frac{1}{\left(x+2\right)\left(x+5\right)}=\frac{3}{20}\)
=>\(\frac{1}{2.5}+\frac{1}{5.8}+\frac{1}{8.11}+...+\frac{1}{\left(x+2\right)\left(x+3\right)}=\frac{3}{20}\)
=>\(3.\left(\frac{1}{2.5}+\frac{1}{5.8}+\frac{1}{8.11}+....+\frac{1}{\left(x+2\right)\left(x+3\right)}\right)=3.\frac{3}{20}\)
=>\(\frac{3}{2.5}+\frac{3}{5.8}+\frac{3}{8.11}+....+\frac{3}{\left(x+2\right)\left(x+3\right)}=\frac{9}{20}\)
=>\(\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{x+2}-\frac{1}{x+3}=\frac{9}{20}\)
=>\(\frac{1}{2}-\frac{1}{x+3}=\frac{9}{20}\)
=>\(\frac{1}{x+3}=\frac{1}{2}-\frac{9}{20}\)
=>\(\frac{1}{x+3}=\frac{1}{20}\)
=>\(x+3=20\)
=>\(x=20-3\)
=>\(x=17\)
\(x\cdot\left(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+....+\frac{1}{45}\right)=88\)
\(x\cdot\left(\frac{2}{\frac{2.3}{2}}+\frac{2}{\frac{3.4}{2}}+\frac{2}{\frac{4.5}{2}}+....+\frac{2}{\frac{9.10}{2}}\right)=88\)
\(x\cdot\left[2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{9}-\frac{1}{10}\right)\right]=88\)
\(x\cdot\left[2\left(\frac{1}{2}-\frac{1}{10}\right)\right]=88\)
\(x\cdot\left(2\cdot\frac{2}{5}\right)=88\)
\(x\cdot\frac{4}{5}=88\)
\(\Rightarrow x=88\div\frac{4}{5}=110\)
Vậy x = 110