2 phần 3 + 2 phần 7 - 2 phần 11
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4 phần 3 + 4 phần 7 - 4 phần 11
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viết rõ lại cái đề giùm tui tui mới làm được
3/7 *14/5 - 1/2 = 6/5-1/2 = 7/10
2/5 - 3/5 *5/10 = 2/5 - 3/10 = 1/10
4/13 *5/11 + 4/13 *6/11 - 4/13
= 4/13*5/11 +4/13 *6/11 - 4/13 *1
= 4/13 *(5/11+ 6/11 - 1)
= 4/13 *0
=0
a,\(\left(\dfrac{-2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\)
\(=\left(-\dfrac{2}{3}+\dfrac{3}{7}\right).\dfrac{5}{4}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right).\dfrac{5}{4}\)
\(=\left(\dfrac{-2}{3}+\dfrac{3}{7}+\dfrac{-1}{3}+\dfrac{4}{7}\right).\dfrac{5}{4}\)
\(=\left(-1+1\right).\dfrac{5}{4}=0\)
Chúc bạn học tốt!!!
Câu b làm tương tự!
a) Đoàn Đức Hiếu
b) \(\dfrac{5}{9}:\left(\dfrac{1}{11}-\dfrac{5}{22}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{2}{3}\right)\)
\(=\dfrac{5}{9}:\left(-\dfrac{3}{22}\right)+\dfrac{5}{9}:\left(-\dfrac{3}{5}\right)\)
\(=-\dfrac{5}{9}\cdot\dfrac{22}{3}-\dfrac{5}{9}\cdot\dfrac{5}{3}\)
\(=-\dfrac{110}{27}-\dfrac{25}{27}\)
\(=-5\)
a) \(\dfrac{3}{5}-\dfrac{3}{5}.\dfrac{2}{3}=\dfrac{3}{5}-\left(\dfrac{3}{5}.\dfrac{2}{3}\right)=\dfrac{3}{5}-\dfrac{2}{5}=\dfrac{1}{5}\)
b) \(\dfrac{-7}{9}.\dfrac{11}{15}-\dfrac{4}{15}.\dfrac{-7}{9}-\dfrac{7}{9}=\dfrac{-7}{9}.\left(\dfrac{11}{15}-\dfrac{4}{15}\right)-\dfrac{7}{9}=\dfrac{-7}{9}.\dfrac{7}{15}-\dfrac{7}{9}=-\dfrac{49}{135}-\dfrac{7}{9}=-\dfrac{154}{135}\)
d) \(3\dfrac{1}{7}-\left(4\dfrac{1}{2}+5\dfrac{3}{7}\right)=\dfrac{22}{7}-\left(\dfrac{9}{2}+\dfrac{38}{7}\right)=\dfrac{22}{7}-\left(\dfrac{63}{14}+\dfrac{76}{14}\right)=\dfrac{22}{7}-\dfrac{139}{14}=\dfrac{44}{14}-\dfrac{139}{14}=-\dfrac{95}{14}\)
Bài 1: Tính
1/ \(\dfrac{-2}{-5}-\left(\dfrac{-4}{3}\right)\)
\(=\dfrac{2}{5}-\left(\dfrac{-4}{3}\right)\)
\(=\dfrac{6}{15}-\left(\dfrac{-20}{15}\right)\)
\(=\dfrac{6-\left(-20\right)}{15}\)
\(=\dfrac{26}{15}\)
2/ \(\left(\dfrac{-2}{4}-\dfrac{1}{2}\right):\dfrac{2}{3}\)
\(=\left(\dfrac{-2}{4}-\dfrac{2}{4}\right):\dfrac{2}{3}\)
\(=-1:\dfrac{2}{3}\)
\(=-1.\dfrac{3}{2}\)
\(=\dfrac{-3}{2}\)
3/ \(\dfrac{5}{12}.\dfrac{17}{11}-\dfrac{5}{12}.\dfrac{7}{11}+\dfrac{5}{12}.\dfrac{1}{11}\)
\(=\dfrac{5}{12}.\left(\dfrac{17}{11}-\dfrac{7}{11}+\dfrac{1}{11}\right)\)
\(=\dfrac{5}{12}.\left(\dfrac{17-7+1}{11}\right)\)
\(=\dfrac{5}{12}.1\)
\(=\dfrac{5}{12}\)
\(a,MSC:3\)
Vì \(2>1\)
\(\Rightarrow\dfrac{2}{3}>\dfrac{1}{3}\)
\(b,MSC:42\\ \dfrac{4}{6}=\dfrac{4.7}{6.7}=\dfrac{28}{42}\\ \dfrac{4}{7}=\dfrac{4.6}{7.6}=\dfrac{24}{42}\)
Vì \(28>24\\ \Rightarrow\dfrac{4}{6}>\dfrac{4}{7}\)
\(c,MSC:22\)
\(\dfrac{6}{11}=\dfrac{6.2}{11.2}=\dfrac{12}{22}=\dfrac{12}{22}\\ \Rightarrow\dfrac{6}{11}=\dfrac{12}{22}\)
\(d,MSC:2\\ 1=\dfrac{2}{2}\)
Vì \(3>2\\ \Rightarrow\dfrac{3}{2}>1\)
\(\frac{\frac{2}{3}+\frac{2}{7}+\frac{2}{11}}{\frac{4}{3}+\frac{4}{7}+\frac{4}{11}}\)
\(=\frac{2\left(\frac{1}{3}+\frac{1}{7}+\frac{1}{11}\right)}{4\left(\frac{1}{3}+\frac{1}{7}+\frac{1}{11}\right)}=\frac{2}{4}=\frac{1}{2}\)
có phải là bài toán như này đúng ko bạn :
2/3 + 2/7 - 2/11
4/3 + 4/7 - 4/11