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\(x-\frac{1}{3}=\frac{9}{20}\)
\(x=\frac{9}{20}+\frac{1}{3}\)
\(x=\frac{9\times3+1\times20}{60}\)
\(x=\frac{47}{60}\)
\(\Rightarrow x\times\left(\frac{1}{2}+\frac{3}{2}\right)=\frac{4}{5}\)
\(\Rightarrow x\times\frac{4}{2}=\frac{4}{5}\)
\(\Rightarrow x\times2=\frac{4}{5}\)
\(\Rightarrow x=\frac{4}{5}\div2\)
\(\Rightarrow x=\frac{4}{5}\times\frac{1}{2}\)
\(\Rightarrow x=\frac{2}{5}\)
\(x\times\frac{1}{2}+\frac{3}{2}\times x=\frac{4}{5}\)
\(x\times\left(\frac{1}{2}+\frac{3}{2}\right)=\frac{4}{5}\)
\(x\times2=\frac{4}{5}\)
\(x=\frac{4}{5}:2\)
\(x=\frac{2}{5}\)
a) \(\frac{16}{35}+\frac{8}{35}=\frac{24}{35}\)
b)\(\frac{160}{77}-\frac{28}{77}=\frac{132}{77}=\frac{12}{1}=12\)
c)\(\frac{72}{180}=\frac{18}{45}\)
d) \(\frac{90}{360}=\frac{1}{4}\)
a) \(\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)\)
\(=\frac{5}{5}+\frac{7}{7}=1+1=2\)
a) \(\frac{3}{5}+\frac{4}{7}+\frac{2}{5}+\frac{1}{7}+\frac{2}{7}\)
\(=\left(\frac{3}{5}+\frac{2}{5}\right)+\left(\frac{4}{7}+\frac{1}{7}+\frac{2}{7}\right)\)
= 1 + 1
= 2
b) \(\frac{4}{9}+\frac{8}{9}+\frac{12}{9}+\frac{16}{9}+...+\frac{48}{9}+\frac{52}{9}+\frac{56}{9}\)
\(=\frac{4+8+12+16+...+48+52+56}{9}\)
Xét 4 + 8 + 12 + 16 + ... + 48 + 52 + 56
Số các số hạng là:
(56 - 4) : 4 + 1 = 14 (số)
4 + 8 + 12 + 16 + ... + 48 + 52 + 56 = (56 + 4) x 14 : 2 = 420
\(\frac{4+8+12+16+...+48+52+56}{9}=\frac{420}{9}=\frac{140}{3}\)
ta có \(\frac{3}{7}=\frac{3\times3}{7\times3}=\frac{9}{21}\)(quy đồng tử)
So sánh \(\frac{9}{21}\)và \(\frac{9}{17}\)ta có:
\(21>17\Rightarrow\frac{9}{17}>\frac{9}{21}\Rightarrow\frac{9}{17}>\frac{3}{7}\)
VẬY: \(\frac{9}{17}>\frac{3}{7}\)
y x 2/3 + 1/3 = 8/9 : 2
Y x 2/3 +1/3 = 4/9
Y x 1/3 = 4/9 - 1/3
y x 1/3 = 1/9
Y = 1/9 : 1/3
y = 1/3
y x 2/3 + 1/3 = 8/9 : 2
y x 2/3 + 1/3 = 4/9
y = (4/9 - 1/3) : 2/3
y = 1/6
( dùng thứ lại biểu thức cộng trừ trước nhân chia sau)
\(\frac{3}{6.8}+\frac{3}{8.10}+.......+\frac{3}{198.200}\)
\(=\frac{3}{2}.\left(\frac{2}{6.8}+\frac{2}{8.10}+........+\frac{2}{198.200}\right)\)
\(=\frac{3}{2}.\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{8}-\frac{1}{10}+........+\frac{1}{198}-\frac{1}{200}\right)\)
\(=\frac{3}{2}.\left(\frac{1}{6}-\frac{1}{200}\right)\)
\(=\frac{3}{2}.\frac{97}{600}=\frac{97}{400}\)
\(3.\left(\frac{2}{6.8}+\frac{2}{8.10}+....+\frac{2}{198.200}\right).\frac{1}{2}\)
=\(3.\left(\frac{1}{6}-\frac{1}{8}+\frac{1}{8}-\frac{1}{10}+...+\frac{198}{200}\right).\frac{1}{2}\)
=\(3.\left(\frac{1}{6}-\frac{1}{200}\right).\frac{1}{2}\)
=.\(3.\frac{97}{600}.\frac{1}{2}\)=97/400
\(\frac{2}{8}+\frac{3}{9}=\frac{18}{72}+\frac{24}{72}=\frac{42}{72}=\frac{7}{12}\)
5 phan 17