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Câu 1a:
75% - 1 1/2 + 0,5 : 5/12 - (-1/2)^2
= 0,75 - 1,5 + 0,5 x 12/5 - 0,25
= (0,75 - 0,25) - 1,5 + 1,2
= 0,5 - 1,5 + 1,2
= - 1 + 1,2
= 0,2
Bài 1b:
(5/7.0,6 - 5: 3 1/2). (40% - 1,4).(-2)^3
= (3/7 - 5 x 2/7).(0,4 - 1,4).8
= - 1.(-1).8
= 8
Bài 1a
- \(\frac45\) : \(\frac87\)
= - \(\frac45\) x \(\frac78\)
= - \(\frac{7}{10}\)
Bài 1b:
- \(\frac38\). \(\frac79\) + \(\frac{-3}{8}\).\(\frac29\) + 0,25
= - \(\frac38\).(\(\frac79+\frac29\)) + 0,25
= - \(\frac38\). 1 + 0,25
= - 0,375 + 0,25
= - 0,125
Bài 1:
Câu a:
2/3.(x -5/6) + 1/4 = 22/9
2/3.(x -5/6) = 22/9 - 1/4
2/3.(x -5/6) = 79/36
x - 5/6 = 79/36 : 2/3
x - 5/6 = 79/24
x = 5/6 + 79/24
x = 33/8
Vậy x = 33/8
Bài 1
a/ −37−(23−37)
\(=\frac{-3}{7}-\frac{2}{3}+\frac{3}{7}\)
\(=\left(\frac{-3}{7}+\frac{3}{7}\right)-\frac{2}{3}\)
\(=0-\frac{2}{3}\)
\(=\frac{-2}{3}\)
a)\(\frac{-7}{25}.\frac{11}{13}+\frac{-7}{25}.\frac{2}{13}-\frac{18}{25}\)
\(=\frac{-7}{25}.\left(\frac{11}{13}+\frac{2}{13}\right)-\frac{18}{25}\)
\(=\frac{-7}{25}.1-\frac{18}{25}\)
\(=-\frac{7}{25}-\frac{18}{25}\)
\(=-1\)
b)\(\frac{5}{7}.\frac{1}{3}-\frac{5}{7}.\frac{1}{4}-\frac{5}{7}.\frac{1}{12}\)
\(=\frac{5}{7}.\left(\frac{1}{3}-\frac{1}{4}-\frac{1}{12}\right)\)
\(=\frac{5}{7}.\left(\frac{4}{12}-\frac{3}{12}-\frac{1}{12}\right)\)
\(=\frac{5}{7}.0\)
\(=0\)
a) \(22\frac{1}{2}\cdot\frac{7}{9}+50\%-1,25\)
\(=\frac{45}{2}\cdot\frac{7}{9}+\frac{50}{100}-\frac{125}{100}\)
\(=\frac{5}{2}\cdot\frac{7}{1}+\frac{1}{2}-\frac{5}{4}\)
\(=\frac{35}{2}+\frac{1}{2}-\frac{5}{4}=18-\frac{5}{4}=\frac{67}{4}\)
b) \(1,4\cdot\frac{15}{49}-\left(\frac{4}{5}+\frac{2}{3}\right):2\frac{1}{5}\)
\(=\frac{7}{5}\cdot\frac{15}{49}-\frac{22}{15}:\frac{11}{15}\)
\(=\frac{1}{1}\cdot\frac{3}{7}-\frac{22}{15}\cdot\frac{15}{11}\)
\(=\frac{3}{7}-2=\frac{3-14}{7}=\frac{-11}{7}\)
c) \(\left(-\frac{1}{2}\right)^2-\frac{7}{16}:\frac{7}{4}+75\%\)
\(=\frac{1}{4}-\frac{7}{16}\cdot\frac{4}{7}+\frac{75}{100}\)
\(=\frac{1}{4}-\frac{1}{4}+\frac{3}{4}=\frac{3}{4}\)
Bài 2 Bạn tự làm nhé
1.a,\(22\frac{1}{2}.\frac{7}{9}+50\%-1,25\)
\(=\frac{45}{2}.\frac{7}{9}+\frac{1}{2}-\frac{5}{4}\)
\(=\frac{35}{2}+\frac{1}{2}-\frac{5}{4}\)
\(=\frac{67}{4}\)
b,Các phép tính khác làm tương tự
Đổi các số ra hết thành phân số,có ngoặc thì lm ngoặc trc,Xoq đến nhân chia trước dồi mới cộng trừ
c,tương tự
2.
a,\(1\frac{3}{5}+\frac{7}{12}\div x=\frac{-9}{4}\)
\(\frac{8}{5}+\frac{7}{12}\div x=\frac{-9}{4}\)
\(\frac{7}{12}\div x=\frac{-77}{20}\)
Đến đây dễ bạn tự làm
b,\(\left(2\frac{4}{5}.x+50\right)\div\frac{2}{3}=-51\)
\(\left(\frac{14}{5}x+50\right)\div\frac{2}{3}=-51\)
\(\frac{14}{5}x+50=-34\)
\(\frac{14}{5}x=-84\)
Tự làm tiếp
c,\(\left|\frac{3}{4}.x-\frac{1}{2}\right|=\frac{1}{4}\)\(\Rightarrow\left|\frac{3}{4}x-\frac{1}{2}\right|=\varnothing\)
a) \(\frac{-3}{7}-\left(\frac{2}{3}-\frac{3}{7}\right)\)
\(=\frac{-3}{7}-\frac{2}{3}+\frac{3}{7}\)
\(=\left(\frac{3}{7}-\frac{3}{7}\right)-\frac{2}{3}\)
\(=0-\frac{2}{3}\)
\(=-\frac{2}{3}\)
b) \(\frac{2}{15}\div\left(\frac{1}{3}.\frac{4}{5}-\frac{1}{3}.\frac{6}{5}\right)\)
\(=\frac{2}{15}\div\left[\frac{1}{3}\left(\frac{4}{5}-\frac{6}{5}\right)\right]\)
\(=\frac{2}{15}\div\left[\frac{1}{3}.\frac{-2}{5}\right]\)
\(=\frac{2}{15}\div\frac{-2}{15}\)
\(=\frac{2}{15}\times\frac{15}{-2}\)
\(=\frac{2}{-2}=-1\)
\(\frac{3}{4}+\frac{1}{4}x=\frac{5}{8}\)
\(\Leftrightarrow\frac{1}{4}x=\frac{5}{8}-\frac{3}{4}\)
\(\Leftrightarrow\frac{1}{4}x=\frac{5}{8}-\frac{6}{8}\)
\(\Leftrightarrow\frac{1}{4}x=\frac{-1}{8}\)
\(\Leftrightarrow x=\frac{-1}{8}\div\frac{1}{4}\)
\(\Leftrightarrow x=\frac{-1}{8}\times\frac{4}{1}\)
\(\Leftrightarrow x=\frac{-4}{8}\)
\(\Leftrightarrow x=\frac{-1}{2}\)
\(25\%x+x=-1,25\)
\(\Leftrightarrow\frac{25}{100}x+x=\frac{-125}{100}\)
\(\Leftrightarrow\frac{1}{4}x+x=\frac{-25}{20}\)
\(\Leftrightarrow x\left(\frac{1}{4}+1\right)=\frac{-5}{4}\)
\(\Leftrightarrow x\left(\frac{1}{4}+\frac{4}{4}\right)=-\frac{5}{4}\)
\(\Leftrightarrow\frac{5}{4}x=\frac{-5}{4}\)
\(\Leftrightarrow x=\frac{-5}{4}\div\frac{5}{4}\)
\(\Leftrightarrow x=\frac{-5}{4}\times\frac{4}{5}\)
\(\Leftrightarrow x=\frac{-5}{5}=-1\)