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7 tháng 6 2018

\(A\times\left(1-\frac{1}{4}\right)\times\left(1-\frac{1}{9}\right)\times\left(1-\frac{1}{16}\right)\times\left(1-\frac{1}{25}\right)=\frac{8}{5}\)

\(A\times\frac{3}{2\times2}\times\frac{2\times4}{3\times3}\times\frac{3\times5}{4\times4}\times\frac{4\times6}{5\times5}=\frac{8}{5}\)

\(A\times\frac{3\times2\times4\times3\times5\times4\times6}{2\times2\times3\times3\times4\times4\times5\times5}=\frac{8}{5}\)

\(A\times\frac{6}{2\times5}=\frac{8}{5}\)

\(A\times\frac{3}{5}=\frac{8}{5}\)

\(A=\frac{8}{5}:\frac{3}{5}\)

\(A=\frac{8}{3}\)

7 tháng 6 2018

ta có: 

A = 8/5 : [(1 - 1/4) x ... x (1 - 1/5)]

    = 8/5 : [3/4 x 8/9 x 15/16 x 24/25]

    = 8/5 : 3/5

    = 8/5 x 5/3

    = 8/3

... là như đề bài nha!

LM
Lê Minh Vũ
CTVHS VIP
7 tháng 7 2023

\(4,7\div0,25+5,3\times4\)

\(=18,8+21,2\)

\(=40\)

\(3\times\left(a-2\right)+150=240\)

\(3\times\left(a-2\right)=90\)

\(a-2=30\)

\(a=32\)

\(\dfrac{1}{9}+a+\dfrac{7}{12}=\dfrac{17}{18}\)

\(\dfrac{1}{9}+a=\dfrac{13}{36}\)

\(a=\dfrac{1}{4}\)

\(\left(\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{1}{3}\times\dfrac{1}{4}+\dfrac{1}{4}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{1}{6}+\dfrac{1}{6}\times\dfrac{1}{7}+\dfrac{1}{7}\times\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)

\(\left(\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+\dfrac{1}{6\times7}+\dfrac{1}{7\times8}\right)\times a=\dfrac{9}{16}\)

\(\left(\dfrac{1}{2}-\dfrac{1}{8}\right)\times a=\dfrac{9}{16}\)

\(\dfrac{3}{8}\times a=\dfrac{9}{16}\)

\(a=\dfrac{3}{2}\)

27 tháng 5

ra nhiều thế

22 tháng 11 2016

a/b nhân 4 cộng 1/6 = 17/6 số phải tìm là bao nhiêu

22 tháng 6 2017

lời giải luôn nhé

LM
Lê Minh Vũ
CTVHS VIP
16 tháng 10 2021

\(\left(1-\frac{1}{4}\right)\times\left(1-\frac{1}{9}\right)\times\left(1-\frac{1}{16}\right)\times\left(1-\frac{1}{25}\right)\times\left(1-\frac{1}{36}\right)\)

\(=\)\(\frac{3}{4}\times\frac{8}{9}\times\frac{15}{16}\times\frac{24}{25}\times\frac{35}{36}\)

\(=\)\(\frac{3\times8\times15\times24\times35}{4\times9\times16\times25\times36}\)

\(=\)\(\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\frac{\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}3\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times4\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times2\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times5\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times3\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times6\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times4\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times5\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times7}{4\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times3\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times3\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times8\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times2\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times5\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times5\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times6\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\text{​​}\times6}\)

\(=\)\(\frac{7\text{​​}\text{​​}\text{​​}\times4}{8\times6}\)

\(=\)\(\frac{7\times4}{4\times2\times6}\)

\(=\)\(\frac{7}{2\times6}\)

\(=\)\(\frac{7}{12}\)

21 tháng 9

a; 

c; \(\dfrac{1}{10}\) + \(\dfrac{4}{20}\) + \(\dfrac{9}{30}\)+\(\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)

\(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)

\(\dfrac{1+2+3+4+5+6+7+8+9}{10}\)

=  \(\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\)

\(\dfrac{10+10+10+10+5}{10}\)

\(\dfrac{\left(10+10+10+10\right)+5}{10}\)

\(\dfrac{10\times4+5}{10}\)

\(\dfrac{45}{10}\)

\(\dfrac{9}{2}\)

6 tháng 10 2017


\(\frac{7}{8}>\frac{7}{9}>\frac{7}{10}>\frac{7}{11}>\frac{7}{15}\)
Tính :
\(a,\frac{1}{4}+\frac{3}{8}+\frac{5}{16}=\frac{4+6+5}{16}=\frac{15}{16}\)
\(b,\frac{3}{5}-\frac{1}{3}-\frac{1}{6}=\frac{18-10-5}{30}=\frac{3}{30}=\frac{1}{10}\)
\(c,\frac{4}{7}\times\frac{5}{8}\times\frac{7}{12}=\frac{5}{14}\times\frac{7}{12}=\frac{5}{24}\)
\(d,\frac{25}{28}:\frac{15}{14}\times\frac{6}{7}=\frac{25\times14\times6}{28\times15\times7}=\frac{5}{7}\)

6 tháng 10 2017

\(\frac{7}{15}< \frac{7}{11}< \frac{7}{10}< \frac{7}{9}< \frac{7}{8}\)

\(a=\frac{15}{16};b=\frac{1}{10}\)

\(c=\frac{5}{24};d=\frac{5}{7}\)