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Tính:
a, 4 - \(\frac{5}{7}\)= \(\frac{23}{7}\)
b, 12 : 3 = 4
c, 578,97 x 307 = 177743,79
d, 266,22 : 34 =7,83
HOK TỐT
BÀi này cậu vận dụng kiến thức về phân số ở Tiểu học
tk mình nhé
Nếu giải ra thì tốn sức lắm
(4/5:6/5:1/y)x30-26=54
=> ( 2/3.y)x30 = 54+26
=> ( 2/3.y)x30=80
=> 2/3.y=80:30
=>2/3.y=8/3
=> y=8/3:2/3
=> y=4
vậy y =4
****
\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}+\frac{1}{3}\right)=\frac{4}{5}.\frac{3}{3}=\frac{4}{5}.1=\frac{4}{5}\)
\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}+\frac{1}{6}\right)=\frac{3}{4}:\frac{2}{3}=\frac{9}{8}\)
\(\frac{2}{3}.\frac{4}{5}-\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}-\frac{1}{3}\right)=\frac{4}{5}.\frac{1}{3}=\frac{4}{15}\)
\(\frac{1}{2}:\frac{3}{4}-\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}-\frac{1}{6}\right)=\frac{3}{4}:\frac{1}{3}=\frac{9}{4}\)
\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\left(\frac{2}{3}+\frac{1}{3}\right).\frac{4}{5}=1.\frac{4}{5}=\frac{4}{5}\)
\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{1}{2}.\frac{4}{3}+\frac{1}{6}.\frac{4}{3}=\left(\frac{1}{2}+\frac{1}{6}\right).\frac{4}{3}=\frac{2}{3}.\frac{4}{3}=\frac{8}{9}\)
c,d tương tự
C1 : \(\frac{7}{11}\):\(\frac{3}{5}\)+\(\frac{4}{11}\):\(\frac{3}{5}\)
=\(\frac{7}{11}\)x\(\frac{5}{3}\)+\(\frac{4}{11}\)x\(\frac{5}{3}\)
=\(\frac{35}{33}\)+\(\frac{20}{33}\)
=\(\frac{55}{33}\)=\(\frac{5}{3}\)
C2: \(\frac{7}{11}\):\(\frac{3}{5}\)+\(\frac{4}{11}\):\(\frac{3}{5}\)
= \(\frac{3}{5}\)x (\(\frac{7}{11}\)+\(\frac{4}{11}\))
=\(\frac{3}{5}\)x 1= \(\frac{3}{5}\)
\(C1:\frac{7}{11}:\frac{3}{5}+\frac{4}{11}:\frac{3}{5}\)
\(=\frac{7}{11}x\frac{5}{3}+\frac{4}{11}x\frac{5}{3}\)
\(=\frac{35}{33}+\frac{20}{33}\)
\(=\frac{55}{33}=\frac{5}{3}\)
\(C2:\frac{7}{11}:\frac{3}{5}+\frac{4}{11}:\frac{3}{5}\)
\(=\frac{7}{11}x\frac{5}{3}+\frac{4}{11}x\frac{5}{3}\)
\(=\frac{5}{3}x\left(\frac{7}{11}+\frac{4}{11}\right)\)
\(=\frac{5}{3}x1=\frac{5}{3}\)
3/5x(2/3-1/5:3/5)
=3/4x(2/3-1/3)
=3/4x1/3=1/4
đúng 100%
\(\frac{3}{4}\cdot\left(\frac{2}{3}-\frac{1}{5}:\frac{3}{5}\right)\)
\(=\frac{3}{4}\cdot\left(\frac{2}{3}-\frac{1}{3}\right)\)
\(=\frac{3}{4}\cdot\frac{1}{3}=\frac{1}{4}\)
\(\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot...\cdot\left(1-\frac{1}{7}\right)\)
\(=\frac{1}{2}\cdot\frac{2}{3}\cdot\frac{3}{4}\cdot\frac{4}{5}\cdot\frac{5}{6}\cdot\frac{6}{7}\)
\(=\frac{\left(1\cdot2\cdot3\cdot4\cdot5\cdot6\right)}{\left(2\cdot3\cdot4\cdot5\cdot6\cdot7\right)}\)
\(=\frac{1}{7}\)
bài làm
a) \(\frac{5}{8}-\frac{2}{5}\)
\(=\frac{25}{40}-\frac{16}{40}\)
\(=\frac{9}{40}\)
b) \(1\frac{1}{10}-\frac{3}{4}\)
\(=\frac{11}{10}-\frac{3}{4}\)
\(=\frac{22}{20}-\frac{15}{20}\)
\(=\)\(\frac{7}{20}\)
c) \(\frac{2}{3}+\frac{1}{2}-\frac{5}{6}\)
\(=\frac{4}{6}+\frac{3}{6}-\frac{5}{6}\)
\(=\frac{4+3-5}{6}\)
\(=\frac{2}{6}\)
\(=\frac{1}{3}\)
chúc bạn học tốt
\(M=\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+\frac{1}{1+2+3+4+5}\)
\(M=\frac{1}{\left(1+2\right).2:2}+\frac{1}{\left(1+3\right).3:2}+\frac{1}{\left(1+4\right).4:2}+\frac{1}{\left(1+5\right).5:2}\)
\(M=\frac{2}{2.3}+\frac{2}{3.4}+\frac{2}{4.5}+\frac{2}{5.6}\)
\(M=2.\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}\right)\)
\(M=2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\right)\)
\(M=2.\left(\frac{1}{2}-\frac{1}{6}\right)\)
\(M=2.\frac{1}{2}-2.\frac{1}{6}\)
\(M=1-\frac{1}{3}=\frac{2}{3}\)
\(8\frac{7}{10}+2\frac{3}{4}=\frac{87}{10}+\frac{11}{4}=\frac{174}{20}+\frac{55}{20}=\frac{229}{20}\)
Bạn chỉ cần đưa về phân số xong tính bình thường. Muốn đổi từ hỗn số sang phân số, ta chỉ cần lấy phần nguyên nhân cho mẫu rồi cộng với tử là xong. Chứ bạn cứ hỏi mấy bài dễ như thế này thì k giỏi đc đâu!!!
4-5/7=23/7
1/2:3=1/6
578,97x307=177743,79
266,22:34=7,83
4-5/7=28/5
1/2:3=1/6
578,97nhân307=177743.79
266,22:34=7.83