So sánh: 12^98 và 55^12.
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12^55
=(3.2^2)^55
=3.2^57 > 2^57
hok tốt
k vs mik chưa đc k nào
Lời giải:
\(A=\frac{98^{12}+1}{98^{13}+1}\\ 98A=\frac{98^{13}+98}{98^{13}+1}=1+\frac{97}{98^{13}+1}> 1+\frac{97}{98^{14}+1}=\frac{98^{14}+98}{98^{14}+1}=98.\frac{98^{13}+1}{98^{14}+1}=98B\)
$\Rightarrow A>B$
A = \(\frac{3}{2}+\frac{7}{6}+\frac{13}{12}+...+\frac{91}{90}+\left(1+\frac{1}{2}\right)+\left(1+\frac{1}{6}\right)+\left(1+\frac{1}{12}\right)+...+\left(1+\frac{1}{90}\right)\)
\(=\left(1+\frac{1}{1.2}\right)+\left(1+\frac{1}{2.3}\right)+\left(1+\frac{1}{3.4}\right)+...+\left(1+\frac{1}{9.10}\right)\)
\(=\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\right)+\left(1+1+1+...+1\right)\)(9 số hạng 1)
\(=\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{9}-\frac{1}{10}\right)+1.9\)
\(=\left(1-\frac{1}{10}\right)+9=10-\frac{1}{10}=\frac{99}{10}>\frac{98}{11}\)
a=1+1/1.2+1+1+1/2.3+....+1+1/9.10
a=1+1+...+1(9 chữ số 1)+1/1-1/2+1/2-1/3+...+1/9-1/10
a=9+1-1/10
a=9+9/10=9+0.9=9.9
b=98/11<98/10=9.8<9.9
=>vậy a>b
\(\frac{4}{6}=\frac{2}{3}\)
\(\frac{18}{27}=\frac{2}{3}\)
\(\Rightarrow\frac{4}{6}=\frac{18}{27}\)
\(\frac{12}{20}=\frac{3}{5}\)
\(\frac{22}{55}=\frac{2}{5}\)
\(\Rightarrow\frac{12}{20}>\frac{22}{55}\)
\(\frac{5}{6}=\frac{10}{12}\)
\(\Rightarrow\frac{5}{6}< \frac{11}{12}\)
Sắp xếp :
4;5;7;8;15;56
HT
\(\frac{4}{6}=\frac{2}{3}\)
\(\frac{18}{27}=\frac{2}{3}\)
\(\Rightarrow\frac{4}{6}=\frac{18}{27}\)
\(\frac{12}{20}=\frac{3}{5}\)
\(\frac{22}{55}=\frac{2}{5}\)
\(\Rightarrow\frac{12}{20}>\frac{22}{55}\)
\(\frac{5}{6}=\frac{10}{12}\)
\(\Rightarrow\frac{5}{6}< \frac{11}{12}\)
Sắp xếp:
4; 5; 7; 8; 15; 56.
_HT_
a=1+1/1.2+1+1/2.3+....+1+1/9.10
a=1+1+...+1(9 chữ số 1) +1/1-1/2+1/2-1/3+..+1/9-1/10
a=9+1-1/10
a=9+9/10=9+0.9=9.9
b=98/11<98/10=9.8<9.9.
vậy a>b
Ta có: a=1+1/2+1+1/6+1+1/12+...+1+1/90=9+1/2+1/6+...+1/90 > 9>99/11> b. Vậy, a>b