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a, \(B=\frac{19^{31}+5}{19^{32}+5}< \frac{19^{31}+5+90}{19^{32}+5+90}=\frac{19^{31}+95}{19^{32}+95}=\frac{19\left(19^{30}+5\right)}{19\left(19^{31}+5\right)}=\frac{19^{30}+5}{19^{31}+5}=A\)
b, Ta có: \(\frac{1}{A}=\frac{2^{20}-3}{2^{18}-3}=\frac{2^2.\left(2^{18}-3\right)+9}{2^{18}-3}=4+\frac{9}{2^{18}-3}\)
\(\frac{1}{B}=\frac{2^{22}-3}{2^{20}-3}=\frac{2^2\left(2^{20}-3\right)+9}{2^{20}-3}=4+\frac{9}{2^{20}-3}\)
Vì \(\frac{9}{2^{18}-3}>\frac{9}{2^{20}-3}\)\(\Rightarrow\frac{1}{A}>\frac{1}{B}\Rightarrow A< B\)
c, Câu hỏi của truong nguyen kim
kieu nay la ko tinh ra ket qua hay so sanh
A=1+C; voi C=5^9/(1+...5^8)=1/(1/5^9+1/5^8+...+1/5)
B=1+D;voi D=3^9/(1+..3^8)=1/(1/3^9+1/3^8+...+1/3)
C=1/E; voi E=(1/5^9+1/5^8+...+1/5)
D=1/f; voi F=(1/3^9+1/3^8+...+1/3)
=> F-E=(1/3-1/5)+...+(1/3^9-1/5^9) >0=> F>E
=> C>D=> A>B
Ta có: \(5\left(1+5+5^2+...+5^9\right)-\left(1+5+5^2+...+5^9\right)\)
= \(\left(5+5^2+5^3+...+5^{10}\right)-\left(1+5+5^2+...+5^9\right)\)
\(4\left(1+5+5^2+...+5^9\right)\)\(=5^{10}-1\)
=> \(1+5+5^2+...+5^9=\frac{5^{10}-1}{4}\)
Tương tự: \(1+5+5^2+....+5^8=\frac{5^9-1}{4}\)
=> \(A=\frac{\frac{5^{10}-1}{4}}{\frac{5^9-1}{4}}=\frac{5^{10}-1}{5^9-1}=\frac{5\left(5^9-1\right)+4}{5^9-1}=5+\frac{4}{5^9-1}>5\)
Tương tự:
\(1+3+3^2+...+3^9=\frac{3^{10}-1}{2}\)
và \(1+3+3^2+...+3^8=\frac{3^9-1}{2}\)
=>\(B=\frac{3^{10}-1}{3^9-1}=\frac{3\left(3^9-1\right)+2}{3^9-1}=3+\frac{2}{3^9-1}< 5\)
=> A > 5 > B
A= \(\frac{1+5+5^2+...+5^9}{1+5+5^2+...+5^8}\)
= \(\frac{1}{1+5+5^2+...+5^8}+\frac{5\left(1+5+5^2+...+5^8\right)}{1+5+5^2+...+5^8}\)
mà \(\frac{1}{1+5+5^2+...+5^8}\approx0\)
suy ra: A= 5.
chứng minh tương tự, ta có: B=3
5 > 3 --> A>B
a) \(\left(-\frac{1}{4}\right)^0=1\)
b) \(\left(-2\frac{1}{3}\right)^2=\left(-\frac{7}{3}\right)^2=\frac{49}{9}\)
c) \(\left(\frac{4}{5}\right)^{-2}=\frac{25}{16}\)
d) \(\left(0,5\right)^{-3}=8\)
e) \(\left(-1\frac{1}{3}\right)^4=\left(-\frac{4}{3}\right)^4=\frac{256}{81}\)
a, \(\left(\frac{-1}{4}\right)^0\) = 1
Bất kỳ số nguyên nào nếu có mũ bằng 0 đều bằng 1
b, \(\left(-2\frac{1}{3}\right)^2=\left(-\frac{7}{3}\right)^2=\frac{49}{9}\)
\(\left(3x-1\right)\left(\frac{-1}{2}x+5\right)=0\)
\(\orbr{\begin{cases}3x-1=0\\\frac{-1}{2}x+5=0\end{cases}}\)
\(\orbr{\begin{cases}x=\frac{1}{3}\\x=10\end{cases}}\)
\(\frac{1}{4}+\frac{1}{3}:(2x-1)=-5\)
\(\Rightarrow\frac{1}{3}:(2x-1)=-5-\frac{1}{4}\)
\(\Rightarrow\frac{1}{3}:(2x-1)=\frac{-21}{4}\)
\(\Rightarrow2x-1=\frac{1}{3}:-\frac{21}{4}\)
\(\Rightarrow2x-1=\frac{1}{3}\cdot-\frac{4}{21}\)
\(\Rightarrow2x-1=\frac{-4}{63}\)
\(\Rightarrow2x=-\frac{4}{63}+1\)
\(\Rightarrow2x=\frac{59}{63}\Leftrightarrow x=\frac{59}{126}\)
Nhấn vào "Đúng 0" lời giải sẽ hiện ra