so sánh: \(\left(\frac{16}{25}\right)^{10}\) và \(\left(\frac{3}{7}\right)^{40}\)
Bài 1 : So sánh
\(\left(\frac{1}{10}\right)^{15}\) và \(\left(\frac{3}{10}\right)^{20}\)
Bài 2 : So sánh
A = \(\left(\frac{13^{15}+1}{13^{16}+1}\right)\) và B = \(\left(\frac{13^{16}+1}{13^{17}+1}\right)\)
Bài 1:
Ta có:
\(\left(\frac{1}{10}\right)^{15}=\left(\frac{1}{5}\right)^{3.5}=\left(\frac{1}{125}\right)^5\)
\(\left(\frac{3}{10}\right)^{20}=\left(\frac{3}{10}\right)^{4.5}=\left(\frac{81}{10000}\right)^5\)
Lại có:
\(\frac{1}{125}=\frac{80}{10000}< \frac{81}{10000}\Rightarrow\left(\frac{1}{125}\right)^5< \left(\frac{81}{10000}\right)^5\)
\(\Rightarrow\left(\frac{1}{10}\right)^{15}< \left(\frac{3}{10}\right)^{20}\)
Bài 2:
Ta có:
\(A=\frac{13^{15}+1}{13^{16}+1}\Rightarrow13A=\frac{13^{16}+13}{13^{16}+1}=1+\frac{12}{13^{16}+1}\)
\(B=\frac{13^{16}+1}{13^{17}+1}\Rightarrow13B=\frac{13^{17}+13}{13^{17}+1}=1+\frac{12}{13^{17}+1}\)
Mà \(\frac{12}{13^{16}+1}>\frac{12}{13^{17}+1}\)
\(\Rightarrow1+\frac{12}{13^{16}+1}>1+\frac{12}{13^{17}+1}\)
\(\Rightarrow13A>13B\Rightarrow A>B\)
so sánh :
C=\(\frac{5^4.20^4}{25^5.4^5}\) và D=\(\left(\frac{-10}{3}\right)^5.\left(\frac{-6}{5}\right)^4\)
E=\(\left(1+\frac{2}{3}-\frac{1}{4}\right).\left(\frac{4}{5}-\frac{3}{4}\right)^2\)và F=\(2:\left(\frac{1}{2}-\frac{2}{3}\right)^3\)
I=\(\frac{2}{3}+\frac{1}{3}:\left(\frac{-8}{25}\right)\)và H=\(\frac{5}{11}.\frac{4}{11}+\frac{7}{11}.\frac{5}{11}-\frac{2}{3}\)
A= \(\frac{\left(81,624:\frac{16}{3}-4,505\right)^2+125.\frac{3}{4}}{\left\{\left[\left(\frac{11}{25}\right)^2:0,88+3,53\right]^2-\left(2,75\right)^2\right\}:\frac{13}{25}}\) B= \(\frac{2^{12}.3^5-4^6.9^2}{\left(2^2.3\right)^6+8^4.3^5}-\frac{5^{10}.7^3-25^5.49^2}{\left(125.7\right)^3+5^9.14^3}\)
So sánh
\(a,\left(-5\right)^{30}\&\left(-3\right)^{50}\)
\(b,\left(\frac{1}{16}\right)^{10}\&\left(\frac{1}{2}\right)^{50}\)
a)
Vì 3<5
\(\Rightarrow3^{30}< 5^{30}\)
\(\Rightarrow\left(-3\right)^{30}< \left(-5\right)^{30}\)
b)
Ta có
\(\left(\frac{1}{2}\right)^{50}=\left[\left(\frac{1}{2}\right)^4\right]^{10}.\left(\frac{1}{2}\right)^{10}\)
\(=\left(\frac{1}{16}\right)^{10}.\left(\frac{1}{2}\right)^{10}\)
Ta có
\(\left(\frac{1}{2}\right)^{10}< 1\)
\(\Leftrightarrow\left(\frac{1}{16}\right)^{10}.\left(\frac{1}{2}\right)^{10}< \left(\frac{1}{16}\right)^{10}\)
\(\Leftrightarrow\left(\frac{1}{2}\right)^{50}< \left(\frac{1}{16}\right)^{10}\)
ta có :\(\left(-5\right)^{30}\) và \(\left(-3\right)^{50}\)là 2 lũy thừa bậc chẵn nên :\(\left(-5\right)^{30}=5^{30}=\left(5^3\right)^{10}=125^{10}\)
\(\left(-3\right)^{50}=3^{50}=\left(3^5\right)^{10}=243^{10}\)
từ trên suy ra (-5)^30<(-3)^50
b) Ta có:\(\left(\frac{1}{2}\right)^{50}=\left(\frac{1}{2^5}\right)^{10}=\left(\frac{1}{32}\right)^{10}\)
\(\Rightarrow\left(\frac{1}{16}\right)^{10}>\left(\frac{1}{2}\right)^{50}\)
ta có :\(\left(-5\right)^{30}\) và \(\left(-3\right)^{50}\)là 2 lũy thừa bậc chẵn nên :\(\left(-5\right)^{30}=5^{30}=\left(5^3\right)^{10}=125^{10}\)
\(\left(-3\right)^{50}=3^{50}=\left(3^5\right)^{10}=243^{10}\)
từ trên suy ra (-5)^30<(-3)^50
b) Ta có:\(\left(\frac{1}{2}\right)^{50}=\left(\frac{1}{2^5}\right)^{10}=\left(\frac{1}{32}\right)^{10}\)
\(\Rightarrow\left(\frac{1}{2}\right)^{50}< \left(\frac{1}{16}\right)^{10}\)
So sánh : \(\left(\frac{1}{-2}\right)^{40}\) và \(\left(\frac{1}{-10}\right)^{12}\)
Cho A = \(\frac{\left(3\frac{2}{5}+\frac{1}{5}\right):2\frac{1}{2}}{\left(5\frac{3}{7}-2\frac{1}{4}\right):4\frac{43}{56}}\)và B = \(\frac{1,2:\left(1\frac{1}{5}-1\frac{1}{4}\right)}{0,32+\frac{2}{25}}\)
So sánh A và B
Ta có
\(A=\frac{\left(3\frac{2}{5}+\frac{1}{5}\right):2\frac{1}{2}}{\left(5\frac{3}{7}-2\frac{1}{4}\right):4\frac{43}{56}}\) \(B=\frac{1,2:\left(1\frac{1}{5}-1\frac{1}{4}\right)}{0,32+\frac{2}{25}}\)
\(\Leftrightarrow A=\frac{\left(\frac{17}{5}+\frac{1}{5}\right):\frac{5}{2}}{\left(\frac{38}{7}-\frac{9}{4}\right):\frac{276}{56}}\) \(\Leftrightarrow B=\frac{\frac{6}{5}:\left(\frac{6}{5}-\frac{5}{4}\right)}{\frac{8}{25}+\frac{2}{25}}\)
\(\Leftrightarrow A=\frac{\frac{18}{5}:\frac{5}{2}}{\frac{89}{28}:\frac{276}{56}}\) \(\Leftrightarrow B=\frac{\frac{6}{5}:\left(-\frac{1}{20}\right)}{\frac{2}{5}}\)
\(\Leftrightarrow A=\frac{\frac{36}{25}}{\frac{89}{138}}\) \(\Leftrightarrow B=\frac{\frac{5}{4}}{\frac{2}{5}}\)
\(\Leftrightarrow A=\frac{4968}{2225}\) \(\Leftrightarrow B=\frac{25}{8}\)
\(\Leftrightarrow A=\frac{39744}{17800}\) \(\Leftrightarrow B=\frac{55625}{17800}\)
Ta có: 39744<55625
\(\Rightarrow A< B\)
Vậy A<B
So sánh \(\left(\frac{1}{63}\right)^7\) và \(\left(\frac{1}{16}\right)^{12}\)
Tính
a,\(\frac{2^{10}\cdot55+2^{10}\cdot26}{2^8\cdot27}\)
b,120:{300:[150-(2.53-23.25)]}
c,\(\left[\left(\frac{40}{130}-\frac{12}{13}\right)\cdot40\%+0,15\right]:\frac{-5}{52}\)
d,\(\frac{0,8:\left(\frac{4}{5}\cdot1,25\right)}{0,64-\frac{1}{25}}+\frac{\left(1,08-\frac{2}{25}\right):\frac{4}{7}}{\left(6\frac{5}{9}-3\frac{1}{4}\right)\cdot2\frac{2}{17}}+\left(1,2+0,5\right):\frac{1}{5}\)
1) so sánh
\(\left(\frac{1}{16}\right)^{10}\)và \(\left(\frac{1}{2}\right)^{50}\)
2) viết các biểu thức sau dưới dạng lũy thừa của một hữu tỉ
a) \(25.5^3.\frac{1}{625}.5^2\)
b) \(4.32:\left(2^3.\frac{1}{16}\right)\)
c) \(5^2.3^5.\left(\frac{3}{5}\right)^2\)
d)\(\left(\frac{1}{7}\right)^2.\frac{1}{7}.49^2\)