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\(\dfrac{48}{25}\cdot\dfrac{27}{55}+2\dfrac{4}{9}\cdot\dfrac{14}{33}\)
\(=\dfrac{1296}{1375}+\dfrac{22}{9}\cdot\dfrac{14}{33}\\ =\dfrac{1296}{1375}+\dfrac{28}{27}\\ =\dfrac{34992}{37125}+\dfrac{38500}{37125}\\ =\dfrac{73492}{37125}\)
\(1\dfrac{19}{22}\cdot\left(\dfrac{47}{77}-\dfrac{16}{15}\right)\\ =\dfrac{41}{22}\cdot\dfrac{-527}{1155}\\ =\dfrac{-21607}{25410}\)
\(\left(3\dfrac{10}{99}+4\dfrac{11}{99}-5\dfrac{8}{299}\right)-\left(\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{6}\right)\\ =\left(\dfrac{307}{99}+\dfrac{37}{99}-\dfrac{1503}{299}\right)-0\\ =\dfrac{344}{99}-\dfrac{1053}{299}\\ =-\dfrac{107}{2277}\)
\(Tìmx:\)
\(a.x:3\frac{1}{15}=1\frac{1}{12}.\)
\(x:\frac{46}{15}=\frac{13}{12}.\)
\(x=\frac{13}{12}.\frac{46}{15}.\)
\(x=\frac{299}{90}.\)
\(Tính:\)
\(a.\frac{41}{42}+\frac{55}{56}+\frac{71}{72}+\frac{89}{90}BCNN=2520.\) \(=\frac{2460}{2520}+\frac{2475}{2520}+\frac{2485}{2520}+\frac{2492}{2520}.\)
\(=\frac{9912}{2520}.\)
\(=\frac{59}{15}.\)
CÂU B CỦA BÀI TÌM X MÌNH CHƯA HỌC NÊN KO BÍT LÀM!
a) x : \(3\frac{1}{5}=1\frac{1}{12}\)
x : \(\frac{16}{5}=\frac{13}{12}\)
x = \(\frac{13}{12}.\)\(\frac{16}{5}\)
x = \(\frac{208}{60}=\frac{52}{15}\)
b) x + 15% . x = 115
x + \(\frac{3}{20}\).x = 115
x.1 + \(\frac{3}{20}.x=115\)
x. (1+\(\frac{3}{20}\))=115
x. \(\frac{23}{20}=115\)
x = \(115:\frac{23}{20}\)
x=100
\(\left[\dfrac{4}{9}+\left(\dfrac{3}{8}x.\left(-\dfrac{1}{2}\right)\right)\right].\dfrac{6}{11}=\dfrac{18}{55}\)
\(\Rightarrow\)\(\left[\dfrac{4}{9}+\left(\dfrac{3}{8}x.\left(-\dfrac{1}{2}\right)\right)\right]=\dfrac{18}{55}:\dfrac{6}{11}\)
\(\Rightarrow\dfrac{4}{9}+\dfrac{3}{8}x.\dfrac{-1}{2}=\dfrac{3}{5}\)
\(\Rightarrow\dfrac{3}{8}x.\dfrac{-1}{2}=\dfrac{3}{5}-\dfrac{4}{9}\)
\(\Rightarrow\dfrac{3}{8}x.\dfrac{-1}{2}=\dfrac{7}{45}\)
\(\Rightarrow\dfrac{3}{8}x=\dfrac{7}{45}:\dfrac{-1}{2}\)
\(\Rightarrow\dfrac{3}{8}x=\dfrac{-14}{45}\)
\(\Rightarrow x=\dfrac{-112}{135}\)
\(A=\frac{16}{3.7}+\frac{16}{7.11}+...+\frac{16}{95.99}\)
\(\Leftrightarrow\frac{1}{4}A=\frac{1}{3}-\frac{1}{99}=\frac{32}{99}\)
\(\Rightarrow A=\frac{32}{99}:\frac{1}{4}=\frac{128}{99}\)
Dấu chấm là dấu nhân nha bạn. Nhớ k mình nha!
4x+x-15=55
=>5x=55+15=70
=>\(x=\dfrac{70}{5}=14\)
= 4.x+x=55-15
=4.x+x=40
=x(4+1)=40
=x.5=40
=x=40:5
=x=8
Chúc bạn học tốt ^^