tính nhanh
(3/5 + 3/7 - 3/11 / 4/4 + 4/7 - 4/11) + 3434/404 = ?
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
\(\frac{\frac{3}{5}+\frac{3}{7}-\frac{3}{11}}{\frac{4}{5}+\frac{4}{7}-\frac{4}{11}}+\frac{3434}{404}=\frac{3\cdot\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}\right)}{4\cdot\left(\frac{1}{5}+\frac{1}{7}-\frac{1}{11}\right)}+\frac{17}{2}=\frac{3}{4}+\frac{17}{2}=\frac{37}{4}\)
1) \(\left(+15\right)+\left(+17\right)=15+17=32\)
2) \(\left(-3\right)+\left(-7\right)=-3-7=-\left(3+7\right)=-10\)
3) \(\left(-25\right)+\left(+4\right)=-25+4=-\left(25-4\right)=-21\)
4) \(\left(-6\right)+\left(-54\right)=-6-54=-\left(6+54\right)=-60\)
5) \(\left(-15\right)+20=20-15=5\)
6) \(\left(-5\right)+8+7+5\)
\(=\left(-5+5\right)+\left(8+7\right)\)
\(=15\)
7) \(\left(-8\right)+\left(-11\right)+\left(-2\right)\)
\(=\left[\left(-8\right)+\left(-2\right)\right]+\left(-11\right)\)
\(=\left(-10\right)+\left(-11\right)\)
\(=-21\)
8) \(15+\left(-5\right)+\left(-14\right)+\left(-16\right)\)
\(=\left[15+\left(-5\right)\right]+\left[\left(-14\right)+\left(-16\right)\right]\)
\(=10+\left(-30\right)\)
\(=-20\)
9) \(\left(-20\right)+\left(-14\right)+3+\left(-86\right)\)
\(=\left[\left(-20\right)+3\right]+\left[\left(-14\right)+\left(-86\right)\right]\)
\(=\left(-17\right)+\left(-100\right)\)
\(=-117\)
10) \(\left(-136\right)+123+\left(-264\right)+\left(-83\right)+240\)
\(=\left[\left(-136\right)+\left(-264\right)\right]+\left[123+\left(-83\right)\right]+240\)
\(=\left(-400\right)+40+240\)
\(=\left(-360\right)+240\)
\(=-120\)
11) \(\left(-596\right)+2001+1999+\left(-404+189\right)\)
\(=\left(-596\right)+2001+1999-404+189\)
\(=\left[\left(-596\right)-404\right]+\left(2001+189\right)+1999\)
\(=\left(-1000\right)+2190+1999\)
\(=1190+1999\)
\(=3189\)
12) \(314+\left(-153\right)+64+121+\left(-247\right)+218\)
\(=\left(314+64+121\right)+\left[\left(-153\right)+\left(-247\right)\right]+218\)
\(=\left(378+121\right)+\left(-400\right)+218\)
\(=499-400+218\)
\(=99+218\)
\(=317\)
\(\text{#}Toru\)
a. A = 2 / 3 . 5 + 2 / 5 . 7 + 2 / 7 . 9 + ... + 2 / 37 . 39
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{37}-\frac{1}{39}=\frac{1}{3}-\frac{1}{39}\)
\(=\frac{13}{39}-\frac{1}{39}=\frac{12}{39}\)
b. B = 4 / 5 . 8 + 4 / 8 . 11 + ... + 4 / 305 . 208
\(=\frac{4}{3}.\left(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{305.308}\right)=\frac{4}{3}.\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{305}-\frac{1}{308}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{5}-\frac{1}{308}\right)=\frac{4}{3}.\frac{303}{1540}=\frac{101}{385}\)
2. a. \(A=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{37}-\frac{1}{39}\)
\(=\frac{1}{3}-\frac{1}{39}=\frac{4}{13}\)
b. \(B=\frac{4}{3}.\left(\frac{3}{5.8}+\frac{3}{8.11}+...+\frac{3}{305.308}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{305}-\frac{1}{308}\right)\)
\(=\frac{4}{3}.\left(\frac{1}{5}-\frac{1}{308}\right)\)
\(=\frac{4}{3}.\frac{303}{1540}=\frac{101}{385}\)
\(\frac{\frac{3}{5}+\frac{3}{7}+\frac{3}{11}}{\frac{4}{5}+\frac{4}{7}+\frac{4}{11}}\)\(=\frac{3.\left(\frac{1}{5}+\frac{1}{7}+\frac{1}{11}\right)}{4.\left(\frac{1}{5}+\frac{1}{7}+\frac{1}{11}\right)}=\frac{3}{4}\)