HT
2
K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Các câu hỏi dưới đây có thể giống với câu hỏi trên
11 tháng 4 2017
a )
\(\frac{2}{7}+\frac{7}{7}.\frac{14}{25}\)
\(=\frac{2}{7}+1.\frac{14}{25}=\frac{2}{7}+\frac{14}{25}\)
\(=\frac{50}{175}+\frac{98}{175}=\frac{148}{175}\)
b)
\(\frac{6}{7}+\frac{5}{7}:5-\frac{8}{9}\)
\(=\frac{6}{7}+\frac{5}{30}-\frac{8}{9}\)
\(=\frac{6}{7}+\frac{1}{6}-\frac{8}{9}\)
\(=\frac{36}{42}+\frac{7}{42}-\frac{8}{9}\)
\(=\frac{43}{42}-\frac{8}{9}=\frac{129}{126}-\frac{112}{126}=\frac{17}{126}\)
tk ủng hộ mk nha!!!!!!!!
17 tháng 4 2017
hực hiện phép nhân hoặc phép chia hai hỗn số bằng cách viết hỗn số dưới dạng phân số:
a) 512.334512.334 b) 613:429613:429
Giải
a) 512.334=112.154=1658;512.334=112.154=1658;
b) 6{1 \over 3}:4{2 \over 9} = {{19} \over 3}:{{38} \over 9} = {{19} \over 3}.{9 \over {38}} = {3 \over 2}\)
Lưu ý: Khi cộng hai hỗn số ta có thể cộng phần nguyên với nhau, phần phân số với nhau. Nhưng nhân (hoặc chia) hai hỗn số ta không thể nhân (hoặc chia) phần nguyên với nhau và phần phân số với nhau.
15 tháng 8 2017
d, \(\dfrac{-5}{9}+\dfrac{3}{5}-\dfrac{3}{9}+\dfrac{-2}{5}\)
\(=\left(\dfrac{-5}{9}+\dfrac{-3}{9}\right)+\left(\dfrac{3}{5}+\dfrac{-2}{5}\right)\)
\(=\dfrac{-8}{9}+\dfrac{1}{5}=-\dfrac{31}{45}\)
e) \(\left(\dfrac{1}{9}-\dfrac{9}{17}\right)+\dfrac{3}{6}-\left(\dfrac{12}{17}-\dfrac{1}{2}\right)+\dfrac{5}{9}\)
\(=\dfrac{1}{9}-\dfrac{9}{17}+\dfrac{3}{6}-\dfrac{12}{17}+\dfrac{1}{2}+\dfrac{5}{9}\)
\(=\left(\dfrac{1}{9}+\dfrac{5}{9}\right)+\left(\dfrac{-9}{17}+\dfrac{-12}{17}\right)+\left(\dfrac{1}{2}+\dfrac{1}{2}\right)\)
\(=\dfrac{2}{3}+\left(-1\right)+1\)
\(=\dfrac{2}{3}+0=\dfrac{2}{3}\)
3 tháng 4 2017
a) Cách 1:
\(3\dfrac{4}{9}+5\dfrac{1}{6}=\left(3+5\right)+\left(\dfrac{4}{9}+\dfrac{1}{6}\right)=8+\dfrac{11}{18}=8\dfrac{11}{18}\)
Cách 2:
\(3\dfrac{4}{9}+5\dfrac{1}{6}=\dfrac{31}{9}+\dfrac{31}{6}=\dfrac{155}{18}=8\dfrac{11}{18}\)
b) Cách 1:
\(8\dfrac{1}{14}-6\dfrac{3}{7}=\left(7-6\right)+\left(\dfrac{15}{14}-\dfrac{3}{7}\right)=1+\dfrac{9}{14}=1\dfrac{9}{14}\)
Cách 2:
\(8\dfrac{1}{14}-6\dfrac{3}{7}=\dfrac{113}{14}-\dfrac{45}{7}=\dfrac{23}{14}=1\dfrac{9}{14}\)
c) Cách 1:
\(7-3\dfrac{6}{7}=\left(6-3\right)+\left(1-\dfrac{6}{7}\right)=3+\dfrac{1}{7}=3\dfrac{1}{7}\)
Cách 2:
\(7-3\dfrac{6}{7}=\dfrac{49}{7}-\dfrac{27}{7}=\dfrac{22}{7}=3\dfrac{1}{7}\)
15 tháng 5 2022
a: \(=\left(\dfrac{37}{9}+\dfrac{13}{4}\right)\cdot\dfrac{9}{4}+\dfrac{11}{4}\)
\(=\dfrac{265}{36}\cdot\dfrac{9}{4}+\dfrac{11}{4}=\dfrac{309}{16}\)
b: \(=1+\dfrac{9-8}{10}:\dfrac{19}{6}\)
\(=1+\dfrac{1}{10}\cdot\dfrac{6}{19}=1+\dfrac{3}{95}=\dfrac{98}{95}\)
5 tháng 3 2018
a) \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+....+\dfrac{1}{99.100}\)
= \(\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+....+\dfrac{1}{99}-\dfrac{1}{100}\)
=\(\dfrac{1}{1}+0+0+...+0-\dfrac{1}{100}\)
=\(1-\dfrac{1}{100}\)
= \(\dfrac{99}{100}\)
VD
6 tháng 3 2018
a) 11.2+12.3+13.4+....+199.10011.2+12.3+13.4+....+199.100
= 11−12+12−13+13−14+....+199−110011−12+12−13+13−14+....+199−1100
=11+0+0+...+0−110011+0+0+...+0−1100
=1−11001−1100
= 99100
20 tháng 4 2017
a) \(\dfrac{8}{5}-\dfrac{9}{5}=\dfrac{8-9}{5}=\dfrac{-1}{5}\)
b) \(\dfrac{5}{2}+\dfrac{2}{3}=\dfrac{15}{6}+\dfrac{4}{6}=\dfrac{15+4}{6}=\dfrac{19}{6}\)
c) \(\dfrac{-5}{9}\cdot\dfrac{2}{11}=\dfrac{-5\cdot2}{9\cdot11}=\dfrac{-10}{99}\)
d) \(\dfrac{-2}{9}:\dfrac{1}{3}=\dfrac{-2}{9}\cdot3=\dfrac{-2}{3}\)
e) \(\dfrac{3}{8}-\dfrac{1}{4}+\dfrac{5}{12}=\dfrac{9}{24}-\dfrac{6}{24}+\dfrac{10}{24}=\dfrac{9-6+10}{24}=\dfrac{13}{24}\)
f) \(\dfrac{-4}{3}\cdot\dfrac{5}{4}:\dfrac{7}{3}=\dfrac{-4}{3}\cdot\dfrac{5}{4}\cdot\dfrac{3}{7}=\dfrac{-4\cdot5\cdot3}{3\cdot4\cdot7}=\dfrac{-5}{7}\)
Q
17 tháng 4 2017
\(A=11\dfrac{3}{13}-\left(2\dfrac{4}{7}+5\dfrac{3}{13}\right)\)
\(A=11\dfrac{3}{13}-5\dfrac{3}{13}-2\dfrac{4}{7}\)
\(A=6-2\dfrac{4}{7}\)
\(A=5\dfrac{7}{7}-2\dfrac{4}{7}\)
\(A=3\dfrac{3}{7}\)
\(B=\left(6\dfrac{4}{9}+3\dfrac{7}{11}\right)-4\dfrac{4}{9}\)
\(B=\left(6\dfrac{4}{9}-4\dfrac{4}{9}\right)+3\dfrac{7}{11}\)
\(B=2+3\dfrac{7}{11}\)
\(B=5\dfrac{7}{11}\)
\(C=\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}-\dfrac{9}{11}+1\dfrac{5}{7}\)
\(C=\dfrac{-5}{7}.\left(\dfrac{2}{11}+1\right)-\dfrac{9}{11}+1\dfrac{5}{7}\)
\(C=\dfrac{-5}{7}.\dfrac{13}{11}-\dfrac{9}{11}+1\dfrac{5}{7}\)
\(C=\dfrac{-65}{77}-\dfrac{9}{11}+1\dfrac{5}{7}\)
\(C=\dfrac{4}{11}+1\dfrac{5}{7}\)
\(C=\dfrac{160}{11}\)
\(D=0,7.2\dfrac{2}{3}.20.0,375.\dfrac{5}{28}\)
\(D=\dfrac{7}{10}.\dfrac{8}{3}.20.\dfrac{375}{1000}.\dfrac{5}{28}\)
\(D=\dfrac{7}{28}=\dfrac{5}{2}\)
\(E=\left(-6,17+3\dfrac{5}{9}-2\dfrac{36}{97}\right)\left(\dfrac{1}{3}-0,25-\dfrac{1}{12}\right)\)
\(E=\left(-6,17+3\dfrac{5}{9}-2\dfrac{36}{97}\right)\left(\dfrac{1}{3}-\dfrac{1}{4}-\dfrac{1}{12}\right)\)
\(E=\left(-6,17+3\dfrac{5}{9}-2\dfrac{36}{97}\right)\left(\dfrac{1}{12}-\dfrac{1}{12}\right)\)
\(E=\left(-6,17+3\dfrac{5}{9}-2\dfrac{36}{97}\right).0\)
\(\Rightarrow E=0\)
\(\dfrac{-13}{18}\)
\(\dfrac{1}{9}\) + \(\dfrac{-5}{6}\)
BCNN (9,6) = 18
18 : 9 = 2 ; 18 : 6 = 3
\(\dfrac{1.2}{9.2}\)= \(\dfrac{2}{18}\) ; \(\dfrac{-5.3}{6.3}\)= \(\dfrac{-15}{18}\)
\(\dfrac{2}{18}\) + \(\dfrac{-15}{18}\) = \(\dfrac{2+\left(-15\right)}{18}\)=\(\dfrac{-13}{18}\)