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\(\Rightarrow x+\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}=\dfrac{47}{42}\\ \Rightarrow x+1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}=\dfrac{47}{42}\\ \Rightarrow x+1-\dfrac{1}{6}=\dfrac{47}{42}\\ \Rightarrow x=\dfrac{47}{42}-\dfrac{5}{6}=\dfrac{2}{7}\)
\(\frac{12}{15}\times\frac{22}{47}+\frac{25}{47}:\frac{15}{12}\)
\(\frac{12}{15}\times\frac{22}{47}+\frac{25}{47}\times\frac{12}{15}\)
\(=\frac{12}{15}\times\left(\frac{22}{47}+\frac{25}{47}\right)\)
\(=\frac{12}{15}\times\frac{22+25}{47}\)
\(=\frac{12}{15}\times1=\frac{12}{15}\)
a) Ta có \(\dfrac{23}{27}>\dfrac{23}{29};\dfrac{23}{29}>\dfrac{22}{29}\)
Vậy \(\dfrac{23}{27}>\dfrac{22}{29}\)
b) Ta có \(\dfrac{15}{25}=1-\dfrac{2}{5}\)
\(\dfrac{25}{49}=1-\dfrac{24}{49}\)
Vì \(\dfrac{2}{5}=\dfrac{24}{60}< \dfrac{24}{49}\)
Vậy \(\dfrac{15}{25}>\dfrac{25}{49}\)
a: =13/26*9/18*2/3=2/3*1/4=2/12=1/6
b: =44/22*5/15*3/2=2*1/3*3/2=2*1/2=1
a) -23/49 = -1081/2303
-25/47 = -1225/2303
=> -1081/2303 > -1225/2303 hay -23/49 > -25/47
b) -317/633 = -235531/470319
-371/743 = -234843/470319
=> -235531/470319 < -234843/470319 hay -317/633 < -371/743
a) \(x+\dfrac{4}{15}=\dfrac{4}{12}\)
\(x=\dfrac{4}{12}-\dfrac{4}{15}\)
\(x=\dfrac{20}{60}-\dfrac{16}{60}\)
\(x=\dfrac{1}{15}\)
b) \(x-\dfrac{5}{8}=1\dfrac{2}{3}\)
\(x-\dfrac{5}{8}=\dfrac{5}{3}\)
\(x=\dfrac{5}{3}+\dfrac{5}{8}\)
\(x=\dfrac{40}{24}+\dfrac{15}{24}\)
\(x=\dfrac{55}{24}\)
\(\dfrac{7}{12}>\dfrac{5}{12}\) (Vì tử số 7>5; phân số cùng mẫu số)
\(\dfrac{2}{5}=\dfrac{2.3}{5.3}=\dfrac{6}{15}\) -> Điền dấu "="
\(\dfrac{7}{10}< \dfrac{7}{9}\) (Vì phân số cùng tử, phân số nào có mẫu số lớn hơn thì phân số đó bé hơn. Ta có: 10>9 => 7/10 < 7/9)
\(\dfrac{7}{12}>\dfrac{5}{12}\)
\(\dfrac{2}{5}=\dfrac{6}{15}\)
\(\dfrac{7}{10}< \dfrac{7}{9}\)
`3+4/9xx7/25xx27/12xx3 4/7-7/25`
`=3+4/9xx7/25xx27/12xx25/7-7/25`
`=3+7/25xx25/7xx4/9xx27/12-7/25`
`=3+4/9xx9/4xx1-7/25`
`=3+1xx1-7/25`
`=3+1-7/25`
`=75/25+25/25-7/25`
`=93/25`
\(M=3+\dfrac{4}{9}\times\dfrac{7}{25}\times\dfrac{27}{12}\times3\dfrac{4}{7}-\dfrac{7}{25}\)
\(=3+\dfrac{4}{9}\times\dfrac{7}{25}\times\dfrac{27}{12}\times\dfrac{25}{7}-\dfrac{7}{25}\)
\(=3+\left(\dfrac{4}{9}\times\dfrac{27}{12}\right)\times\left(\dfrac{7}{25}\times\dfrac{25}{7}\right)-\dfrac{7}{25}\)
\(=3+\left(\dfrac{4\times3\times9}{9\times3\times4}\right)\times1-\dfrac{7}{25}\)
\(=3+1\times1-\dfrac{7}{25}\)
\(=3+1-\dfrac{7}{25}\)
\(=4-\dfrac{7}{25}\)
\(=\dfrac{100}{25}-\dfrac{7}{25}\)
\(=\dfrac{93}{25}\)
cái này là toán đó nha mik ghi nhầm
12/15. 22/47+25/47:15/12
=12/15.22/47+25/47.12/15
=12/15.(22/47+25/47)
=12/15.1
=12/15
(. nghĩa là nhân)