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hỗn số thì tử phải lớn hơn mẫu thì chia tử với mẫu thì mới ra hỗn số
a)\(\frac{2}{3}+\frac{3}{4}+\frac{5}{6}\)
\(=\frac{8+9+10}{12}\)
\(=\frac{27}{12}=\frac{9}{4}\)
b)\(\frac{15}{8}-\frac{7}{12}+\frac{5}{6}\)
\(=\frac{45-14+20}{24}\)
\(=\frac{51}{24}=\frac{17}{8}\)
2)
a)\(\frac{2}{5}+\frac{7}{13}+\frac{3}{5}+\frac{1}{7}\)
\(=\frac{2}{5}+\frac{3}{5}+\frac{7}{13}+\frac{1}{7}\)
\(=1+\frac{7}{13}+\frac{1}{7}\)
\(=\frac{20}{13}+\frac{1}{7}\)
\(=\frac{153}{91}\)
Tí tớ trả lời tiếp
b)\(5\frac14+3\frac25-4\frac14\)
=\(\left(5\frac14-4\frac14\right)+3\frac25\)
=\(\left\lbrack\left(5-4\right)+\left(\frac14-\frac14\right)\right\rbrack+\frac{17}{5}\)
=\(1+0+\frac{17}{5}\)
=\(\frac55+\frac{17}{5}\)
=\(\frac{22}{5}\)
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,\(\left|\frac{3}{4}.x-\frac{1}{2}\right|=\frac{1}{4}\)\(\Rightarrow\left|\frac{3}{4}x-\frac{1}{2}\right|=\varnothing\)
Sai đâu bỏ qua nhé, hơi to mới lại mk tính máy tính ra : \(\frac{77}{30}\)nên ko chắc nhé
\(2+\frac{1}{1+\frac{1}{1+\frac{1}{3+\frac{1}{4}}}}=2+\frac{1}{1+\frac{1}{1+\frac{1}{\frac{13}{4}}}}\)
\(=2+\frac{1}{1+\frac{1}{1+\frac{4}{13}}}=2+\frac{1}{1+\frac{1}{\frac{17}{3}}}\)
\(=2+\frac{1}{1+\frac{3}{17}}=2+\frac{1}{\frac{20}{17}}=2+\frac{17}{20}=\frac{57}{20}\)
a) \(\frac{3}{2}+\left(6-\frac{3}{2}\right)\)
\(=\frac{3}{2}+6-\frac{3}{2}\)
\(=\left(\frac{3}{2}-\frac{3}{2}\right)+6\)
\(=0+6\)
\(=6\)
b) \(\frac{7}{3}-\frac{4}{3}:4+1\frac{1}{2}\)
\(=\frac{7}{3}-\frac{1}{3}+\frac{3}{2}\)
\(=2+\frac{3}{2}\)
\(=\frac{7}{2}\)
_Chúc bạn học tốt_
a) \(\frac{3}{2}+\left(6-\frac{3}{2}\right)\)
\(=\frac{3}{2}+6-\frac{3}{2}\)
\(=\frac{3}{2}-\frac{3}{2}+6\)
\(=0+6=6\)
Đây là cách tính nhanh nha
\(\frac{7}{3}-\frac{4}{3}:4+1\frac{1}{2}\)
\(=\frac{7}{3}-\frac{4}{3}.\frac{1}{4}+\frac{3}{2}\)
\(=\frac{7}{3}-\frac{1}{3}+\frac{3}{2}\)
\(=\frac{6}{3}+\frac{3}{2}\)
\(=\frac{12+9}{6}\)
\(=\frac{21}{6}\)
\(=\frac{7}{2}\)
Cần lắm ko
Đỗ Ngọc Hải cần gấp
Đúng 0
\(=\frac{1}{\frac{2.3}{2}}+\frac{1}{\frac{3.4}{2}}+\frac{1}{\frac{4.5}{2}}+...+\frac{1}{\frac{50.51}{2}}=2\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{50.51}\right)\)
\(=2.\left(\frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}+...+\frac{51-50}{50.51}\right)=2\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{50}-\frac{1}{51}\right)\)
\(=2\left(\frac{1}{2}-\frac{1}{51}\right)=1-\frac{2}{51}=\frac{49}{51}\)
quên cách làm rồi
\(\frac{1}{1+2}+\frac{1}{1+2+3}+...+\frac{1}{1+2+3+...+50}\)
Ta có. \(\frac{2}{2.\left(1+2\right)}+\frac{2}{2.\left(1+2+3\right)}+...+\frac{2}{2.\left(1+2+...+50\right)}\)
= \(\frac{2}{6}+\frac{2}{12}+\frac{2}{20}+...+\frac{2}{2550}\)
= \(\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{50.51}\)
= 2.( \(\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{50.51}\))
= 2. (\(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{50}-\frac{1}{51}\))
= 2. ( \(\frac{1}{2}-\frac{1}{51}\))
= 2. ( \(\frac{51}{102}-\frac{2}{102}\))
= 2. \(\frac{49}{102}\)
= \(\frac{49}{51}\)
\(\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+...+\frac{1}{1+2+3+...+50}\)
\(=\frac{1}{\frac{\left(1+2\right).2}{2}}+\frac{1}{\frac{\left(1+3\right).3}{2}}+\frac{1}{\frac{\left(1+4\right).4}{2}}+...+\frac{1}{\frac{\left(1+50\right).50}{2}}\)
\(=1:\frac{3.2}{2}+1:\frac{4.3}{2}+1:\frac{5.4}{2}+...+1:\frac{51.50}{2}\)
\(=1.\frac{2}{3.2}+1.\frac{2}{4.3}+1.\frac{2}{5.4}+...+1.\frac{2}{51.50}\)
\(=\frac{2}{3.2}+\frac{2}{4.3}+\frac{2}{5.4}+...+\frac{2}{51.50}\)
\(=2.\left(\frac{1}{3.2}+\frac{1}{4.3}+\frac{1}{5.4}+...+\frac{1}{51.50}\right)\)
\(=2.\left(\frac{3-2}{3.2}+\frac{4-3}{4.3}+\frac{5-4}{5.4}+...+\frac{51-50}{51.50}\right)\)
\(=2.\left(\frac{3}{2.3}-\frac{2}{2.3}+\frac{4}{4.3}-\frac{3}{4.3}+\frac{5}{5.4}-\frac{4}{5.4}+...+\frac{51}{51.50}-\frac{50}{50.51}\right)\)
\(=2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{50}-\frac{1}{51}\right)\)
\(=2.\left(\frac{1}{2}-\frac{1}{51}\right)\)
\(=2.\left(\frac{51}{102}-\frac{2}{102}\right)\)
\(=2.\frac{49}{102}\)
\(=\frac{49}{51}\)
49/51