Tính hợp lý
a) − 3 10 − 6 11 − 21 30 − 5 11
b) 13 5 + 7 16 − 11 16 − 12 10
K
Khách
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KT
3
N
24 tháng 6 2019
\(a)-\left(\frac{3}{10}-\frac{6}{11}\right)-\left(\frac{21}{30}-\frac{5}{11}\right)\)
\(=-\frac{3}{10}+\frac{6}{11}-\frac{21}{30}+\frac{5}{11}\)
\(=\left(-\frac{3}{10}-\frac{21}{30}\right)+\left(\frac{6}{11}+\frac{5}{11}\right)\)
\(=-1+1\)
\(=0\)
\(b)\left(\frac{13}{5}+\frac{7}{16}\right)-\left(\frac{11}{16}-\frac{12}{10}\right)\)
\(=\frac{13}{5}+\frac{7}{16}-\frac{11}{16}+\frac{12}{10}\)
\(=\left(\frac{13}{5}+\frac{12}{10}\right)+\left(\frac{7}{16}-\frac{11}{16}\right)\)
\(=\frac{19}{5}+\left(-\frac{1}{4}\right)\)
\(=\frac{71}{20}\)
24 tháng 6 2019
a) \(-\left(\frac{3}{10}-\frac{6}{11}\right)-\left(\frac{21}{30}-\frac{5}{11}\right)\)
\(=\frac{-3}{10}+\frac{6}{11}-\frac{21}{30}+\frac{5}{11}\)
\(=\left(\frac{-3}{10}-\frac{21}{30}\right)+\left(\frac{6}{11}+\frac{5}{11}\right)\)
\(=\left(\frac{-9}{30}-\frac{21}{30}\right)+1\)
\(=-1+1\)
= 0
b) \(\left(\frac{13}{5}+\frac{7}{16}\right)-\left(\frac{11}{16}-\frac{12}{10}\right)\)
\(=\frac{13}{5}+\frac{7}{16}-\frac{11}{16}+\frac{12}{10}\)
\(=\left(\frac{13}{5}+\frac{12}{10}\right)+\left(\frac{7}{16}-\frac{11}{16}\right)\)
\(=\left(\frac{26}{10}+\frac{12}{10}\right)-4\)
= \(\frac{19}{5}-4\)
= \(\frac{-1}{5}\)
27 tháng 4 2020
BÀI 1
a, \(5\times\frac{-7}{10}=\frac{-35}{10}=\frac{-7}{2}\)
b, \(\frac{4}{5}\times\frac{-7}{10}=\frac{-28}{50}=\frac{-14}{25}\)
c, \(\frac{4}{9}+\frac{4}{3}\times\frac{16}{4}=\frac{4}{9}+\frac{16}{3}=\frac{52}{9}\)
d, \(\frac{11}{22}-\frac{3}{9}\times\frac{14}{21}=\frac{11}{22}-\frac{2}{9}=\frac{55}{198}=\frac{5}{18}\)
BÀI 2
\(A=\frac{6}{13}\times\frac{5}{7}+\frac{6}{13}\times\frac{2}{7}+\frac{17}{13}\)
\(A=\frac{30}{91}+\frac{12}{91}+\frac{17}{13}\)
\(A=\frac{30}{91}+\frac{12}{91}+\frac{119}{91}\)
\(A=\frac{161}{91}=\frac{23}{13}\)
\(B=\frac{11}{15}\times\frac{4}{11}+\frac{11}{15}\times\frac{5}{11}+\frac{11}{15}\times\frac{2}{11}\)
\(B=\frac{4}{15}+\frac{1}{3}+\frac{2}{15}\)
\(B=\frac{11}{15}\)
\(C=\left(\frac{19}{64}-\frac{33}{22}+\frac{24}{51}\right)\times\left(\frac{1}{5}-\frac{1}{15}-\frac{2}{15}\right)\)
\(C=\frac{-797}{1088}\times0\)
\(C=0\)
\(D=\frac{8}{13}\times\frac{7}{12}+\frac{8}{13}\times\frac{5}{12}-\frac{1}{12}\)
\(D=\frac{14}{39}+\frac{10}{39}-\frac{1}{12}\)
\(D=\frac{83}{156}\)
LT
3 tháng 10 2021
bạn biết câu náy không (24 + 11) . {546 - [14 . (64 - 2^{3}3) : 2]} =
23 tháng 6 2016
Bài 2 :
Ta có:
A) | 2 + 3x | = | 4x - 3 |
<=> 2 + 3x = 4x - 3
<=> 3x - 4x = -3 - 2
=> -x = -5
=> x= 5
9 tháng 10 2016
Bạn dùng công thức này mà làm nhé :\(\frac{n}{a\times\left(a+n\right)}=\frac{1}{a}-\frac{1}{a+n}\)
Ví dụ :\(\frac{2}{3\times5}=\frac{1}{3}-\frac{1}{5};\frac{3}{4\times7}=\frac{1}{4}-\frac{1}{7};\frac{5}{6\times11}=\frac{1}{6}-\frac{1}{11}\)
22 tháng 12 2021
1+2+3+4+5+6+7+8+9+10=55
11+12+13+14+15+16+17+18+19+20=155
1+2+3+4+5+6+7+8+9+10+11+12+13+14 +15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30-50-53=362
22 tháng 12 2021
1+2+3+4+5+6+7+8+9+10=55
11+12+13+14+15+16+17+18+19+20=155
1+2+3+4+5+6+7+8+9+10+11+12+13+14 +15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30-50-53=362
O
9 tháng 5 2022
a) \(\dfrac{7}{30}+\dfrac{\left(-12\right)}{37}+\dfrac{23}{30}+\dfrac{\left(-25\right)}{37}=\left(\dfrac{7}{30}+\dfrac{23}{30}\right)+\left(\dfrac{-12}{37}+\dfrac{-25}{37}\right)=1+\left(-1\right)=0\)
b) \(\dfrac{5}{7}\cdot\dfrac{5}{11}+\dfrac{5}{7}\cdot\dfrac{2}{11}-\dfrac{5}{7}\cdot\dfrac{14}{11}=\dfrac{5}{7}\cdot\left(\dfrac{5}{11}+\dfrac{2}{11}-\dfrac{14}{11}\right)=\dfrac{5}{7}\cdot\left(-\dfrac{7}{11}\right)=-\dfrac{5}{11}\)
c) \(\dfrac{\left(-5\right)}{7}\cdot\dfrac{3}{13}-\dfrac{5}{7}\cdot\dfrac{10}{13}+1\dfrac{5}{7}=\dfrac{5}{7}\cdot\dfrac{-3}{13}-\dfrac{5}{7}\cdot\dfrac{10}{13}+\dfrac{12}{7}=\dfrac{5}{7}\cdot\left(\dfrac{-3}{13}-\dfrac{10}{13}\right)+\dfrac{12}{7}=\dfrac{5}{7}\cdot\left(-1\right)+\dfrac{12}{7}=\left(-\dfrac{5}{7}\right)+\dfrac{12}{7}=\dfrac{7}{7}=1\)
a)
− 3 10 − 6 11 − 21 30 − 5 11 = − 3 10 + 6 11 − 7 10 + 5 11 = − 3 10 − 7 10 + 6 11 + 5 11 = − 1 + 1 = 0
b)
13 5 + 7 16 − 11 16 − 12 10 = 13 5 + 7 16 − 11 16 + 6 5 = 13 5 + 6 5 + 7 16 − 11 16 = 19 5 + − 1 4 = 76 20 + − 5 20 = 71 20