1/18+2/17+....+18/1+18
----------------------------------
1/18+1/7+......+1/1
Chú ý: dấu --------------- là phân số
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4/6 + 7/18 + 17/9 + 14/6 + 1/9
= 12/18 + 7/18 + 34/18 + 42/18 + 2/18
= ( 34/18 + 2/18 ) + ( 42/18 + 12/18 ) + 7/18
= 36/18 + 54/18 + 7/18
= 97/18
Trl:
\(\frac{4}{6}+\frac{7}{18}+\frac{17}{9}+\frac{14}{6}+\frac{1}{9}\)
\(=\frac{12}{18}+\frac{7}{18}+\frac{34}{18}+\frac{42}{18}+\frac{2}{18}\)
\(=\left(\frac{34}{18}+\frac{2}{18}\right)+\left(\frac{42}{18}+\frac{12}{18}\right)+\frac{7}{18}\)
\(=\left(\frac{36}{18}+\frac{54}{18}\right)+\frac{7}{18}\)
\(=\frac{90}{18}+\frac{7}{18}=\frac{97}{18}\)
#z
bài2 \(x\times\dfrac{15}{16}-x\times\dfrac{4}{16}=2\)
\(x\times\dfrac{11}{16}=2\)
\(x=2:\dfrac{11}{16}\)
\(x=\dfrac{32}{11}\)
Bài 1 :
\(\dfrac{x}{16}\times\left(2017-1\right)=2\)
\(\dfrac{x}{16}\times2016=2\)
\(\dfrac{x}{16}=\dfrac{2}{2016}\)
\(x=\dfrac{2}{2016}\times16\)
\(x=\dfrac{1}{63}\)
5/9 <1 ; 11/7 >1 ; 17/18<1 ; 1> 5/9 ; 1<11/7 ; 1>17/18
tick cho mình nhé
c1 :ta thấy : 5 / 6 bé hơn 1
6 / 5lon hơn 1 nên 6/5 lớn hơn 5/6
c2 5/6=5*5/6*5=25/30
6/5=6*6/5*6=36/30 ma 25 < 36 nen 5/6 < 6/5
a, \(A=\frac{17^{18}+1}{17^{19}+1}< 1\)
\(A=\frac{17^{18}+1}{17^{19}+1}< \frac{17^{18}+1+16}{17^{19}+1+16}=\frac{17^{18}+17}{17^{19}+17}=\frac{17(17^{17}+1)}{17(17^{18}+1)}=B\)
\(\Rightarrow A< B\)
b, Tương tự câu a
a)Ta có : A = \(\frac{17^{18}+1}{17^{19}+1}< \frac{17^{18}+1+16}{17^{19}+1+16}=\frac{17^{18}+17}{17^{19}+17}=\frac{17\left(17^{17}+1\right)}{17\left(17^{18}+1\right)}=\frac{17^{17}+1}{17^{18}+1}\) = B
Vậy A < B
b) Làm tương tự như câu A
a)\(\frac{-5}{18}+\frac{32}{45}-\frac{9}{10}\)
\(=\frac{-25}{90}+\frac{64}{90}-\frac{81}{90}\)
\(=-\frac{42}{90}=-\frac{7}{15}\)
b)\(\frac{3}{4}-\left(-\frac{5}{8}\right)+\frac{9}{4}-\frac{3}{16}\)
\(=\frac{3}{4}+\frac{5}{8}+\frac{9}{4}-\frac{3}{16}\)
\(=\frac{12}{16}+\frac{10}{16}+\frac{36}{16}-\frac{3}{16}\)
\(=\frac{58}{16}=\frac{29}{8}\)
c) \(\frac{11}{125}-\frac{17}{18}-\frac{5}{7}+\frac{4}{9}+\frac{17}{14}=\frac{11}{125}\)
d) \(\frac{-2}{5}-\frac{3}{10}-\left(-\frac{1}{2}\right)\)
\(=-\frac{2}{5}-\frac{3}{10}+\frac{1}{2}\)
\(=-\frac{4}{10}-\frac{3}{10}+\frac{5}{10}\)
\(=-\frac{2}{10}=-\frac{1}{5}\)
Xét tử số
1/18+2/17+3/16+...+18/1+18
=[(1/18)+1]+[(2/17)+1]+[(3/16)+1]+...+[(18/1)+1]
=19/18+19/17+19/16+...+19/1
=19.[(1/18)+(1/17)+(1/16)+...+1/1]
=>phân số trên bằng 19