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\(3\frac{5}{11}+\frac{4}{17}-\frac{5}{11}-\frac{3}{17}\)
\(=\left(3\frac{5}{11}-\frac{5}{11}\right)+\left(\frac{4}{17}-\frac{3}{17}\right)\)
\(=3+\frac{1}{17}\)
\(=\frac{51}{17}+\frac{1}{17}\)
\(=\frac{52}{17}\)
Chúc bạn học tốt !!!
13/17 : 2/5 - 11/7 : 2/5 = ( 13/17- 11/7 ) : 2/5
=(91/119 - 187/119) : 2/5
= -96/119 : 2/5
= -96/119 x 5/2
= -240/119
\(\frac{13}{17}:\frac{2}{5}-\frac{11}{7}:\frac{2}{5}\)
\(=\frac{13}{17}.\frac{5}{2}-\frac{11}{7}.\frac{5}{2}\)
\(=\frac{5}{2}.\left(\frac{13}{17}-\frac{11}{7}\right)\)
\(=\frac{5}{2}.\frac{-96}{119}\)
\(=\frac{-240}{119}\)
\(\dfrac{1}{3\times7}+\dfrac{1}{7\times11}+\dfrac{1}{11\times15}+...+\dfrac{1}{a\times\left(a+4\right)}=\dfrac{50}{609}\)
\(\dfrac{1}{4}\times\left(\dfrac{4}{3\times7}+\dfrac{4}{7\times11}+...+\dfrac{4}{a\times\left(a+4\right)}\right)=\dfrac{50}{609}\)
\(\dfrac{1}{3}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+...+\dfrac{1}{a}-\dfrac{1}{a\times4}=\dfrac{50}{609}\div\dfrac{1}{4}\)
\(\dfrac{1}{3}-\dfrac{1}{a\times4}=\dfrac{200}{609}\)
\(\dfrac{1}{a\times4}=\dfrac{1}{3}-\dfrac{200}{609}\)
\(\dfrac{1}{a\times4}=\dfrac{1}{203}\)
\(a\times4=203\)
\(a=\dfrac{203}{4}\)
\(\dfrac{1}{3\times7}\)+\(\dfrac{1}{7\times11}\)+\(\dfrac{1}{11\times15}\)+...+\(\dfrac{1}{a\times\left(a+4\right)}\) = \(\dfrac{50}{609}\)
4\(\times\)( \(\dfrac{1}{3\times7}\) +\(\dfrac{1}{7\times11}\)+\(\dfrac{1}{11\times15}\)+...+\(\dfrac{1}{a\times\left(a+4\right)}\)) = \(\dfrac{50}{609}\) \(\times\)4
\(\dfrac{4}{3\times7}\)+ \(\dfrac{4}{7\times11}\)+\(\dfrac{1}{11\times15}\)+...+\(\dfrac{4}{a\times\left(a+4\right)}\) = \(\dfrac{50}{609}\) \(\times\) 4
\(\dfrac{1}{3}\) - \(\dfrac{1}{7}\) + \(\dfrac{1}{7}\) - \(\dfrac{1}{11}\) + \(\dfrac{1}{11}\)-\(\dfrac{1}{15}\)+...+\(\dfrac{1}{a}\)-\(\dfrac{1}{a+4}\) = \(\dfrac{200}{609}\)
\(\dfrac{1}{3}\) - \(\dfrac{1}{a+4}\) = \(\dfrac{200}{609}\)
\(\dfrac{1}{a+4}\) = \(\dfrac{1}{3}\) - \(\dfrac{200}{609}\)
\(\dfrac{1}{a+4}\) = \(\dfrac{1}{203}\)
a + 4 = 203
\(a\) = 203 - 4
\(a\) = 199
Đáp số: \(a\) = 199
Bài làm :
\(3\frac{5}{11}+\frac{4}{17}-\frac{5}{11}-\frac{3}{17}\)
\(=3+\frac{5}{11}+\frac{4}{17}-\frac{5}{11}-\frac{3}{17}\)
\(=3+\frac{1}{17}\)
\(=\frac{52}{17}\)
Học tốt nhé
Bài làm :
Ta có :
\(...=\left(\frac{38}{11}-\frac{5}{11}\right)+\left(\frac{4}{17}-\frac{3}{17}\right)=\frac{33}{11}+\frac{1}{17}=1=3+\frac{1}{17}=3\frac{1}{17}=\frac{52}{17}\)