\(\dfrac{3}{5}+\dfrac{5}{7}\) x \(\dfrac{3}{5}-\dfrac{9}{7}\) x \(\dfrac{3}{5}\)

\(=\dfrac{3}{5}+\left(\dfrac{5}{7}-\dfrac{9}{7}\right)\) x \(\dfrac{3}{5}\)

\(=\dfrac{3}{5}-\dfrac{4}{7}\) x \(\dfrac{3}{5}\)

\(=\dfrac{3}{5}-\dfrac{12}{35}\)

\(=\dfrac{21}{35}-\dfrac{12}{35}=\dfrac{21-12}{35}=\dfrac{9}{35}\)

=(24/100+60/100+76/100+25/100).(26/7+9/7)
=37/20.5
=37/4
k cho mình nha

à quên đề bài là " TÍNH " 

2(x - 7) - 3(x + 8) = 5

=> 2x - 14 - 3x - 24 = 5

=> -x - 38 = 5

=> -x = 5 + 38

=> -x = 43

=> x = -43

=>2x -14 -3x - 24 =5

=>  x = -43

sao hong ai dê y vay troi

mình viết tắt bạn tự hiểu nha:

a=1+(5⁹/1+5+5²5+...+5⁸

b=1+(3⁹/1+3+3³+....+3⁸

VD:A/B-C/D=A.C/B.D-C.B/D.B

TƯƠNG TỰ NHƯ A,B BẠN TÍNH RA

Ta có: \(20\%\cdot x+\frac58x\cdot0,5=\frac{11}{26}\)

=>\(x\cdot\frac15+x\cdot\frac58\cdot\frac12=\frac{11}{26}\)

=>\(x\left(\frac15+\frac{5}{16}\right)=\frac{11}{26}\)

=>\(x\cdot\frac{41}{80}=\frac{11}{26}\)

=>\(x=\frac{11}{26}:\frac{41}{80}=\frac{11}{26}\cdot\frac{80}{41}=\frac{11\cdot40}{41\cdot13}=\frac{440}{533}\)

\(B\left(5\right)=\left\{0;5;10;15;20;...\right\}\)

\(B\left(-5\right)=\left\{0;-5;-10;-15;-20;...\right\}\)

\(\dfrac{5}{4\times7}+\dfrac{5}{7\times10}+....+\dfrac{5}{25\times28}+\dfrac{5}{28\times31}\)

\(=5\times\left(\dfrac{1}{4\times7}+\dfrac{1}{7\times10}+...+\dfrac{1}{28\times31}\right)\)

\(=\dfrac{5}{3}\times\left(\dfrac{3}{4\times7}+\dfrac{3}{7\times10}+....+\dfrac{3}{28\times31}\right)\)

\(=\dfrac{5}{3}\times\left(\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+...+\dfrac{1}{28}-\dfrac{1}{31}\right)\)

\(=\dfrac{5}{3}\times\left(\dfrac{1}{4}-\dfrac{1}{31}\right)\)

\(=\dfrac{5}{3}\times\dfrac{27}{124}\)

\(=\dfrac{45}{124}\)

`#3107`

\(\dfrac{5}{4\times7}+\dfrac{5}{7\times10}+...+\dfrac{5}{25\times28}+\dfrac{5}{28\times31}\)

\(=\dfrac{5}{3}\times\left(\dfrac{3}{4\times7}+\dfrac{3}{7\times10}+...+\dfrac{3}{25\times28}+\dfrac{3}{28\times31}\right)\)

\(=\dfrac{5}{3}\times\left(\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{10}+...+\dfrac{1}{28}-\dfrac{1}{31}\right)\\ =\dfrac{5}{3}\times\left(\dfrac{1}{4}-\dfrac{1}{31}\right)\\ =\dfrac{5}{3}\times\dfrac{27}{124}\\ =\dfrac{45}{124}\)

Vì 1⁵= 1⁶ nên x - 5 = 1

x= 1+5

x=6

\(\left(x-5\right)^5=\left(x-5\right)^6\)

\(\Rightarrow\left(x-5\right)^6-\left(x-5\right)^5=0\)

\(\Rightarrow\left(x-5\right)^5.\left(x-5-1\right)=0\)

\(\Rightarrow\left(x-5\right)^5.\left(x-6\right)=0\)

\(\Rightarrow\left\{{}\begin{matrix}\left(x-5\right)^5=0\\x-6=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=5\\x=6\end{matrix}\right.\)

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\(3A=5+\dfrac{5}{3}+\dfrac{5}{3^2}+...+\dfrac{5}{3^{19}}\)

\(2A=3A-A=5-\dfrac{5}{3^{20}}\)

\(A=\dfrac{5.3^{20}-5}{2.3^{20}}\)