Ta có:
\(\left(\dfrac{1}{2}\right)^{2n-1}=\dfrac{1}{8}=\left(\dfrac{1}{2}\right)^3\)
\(\Rightarrow2n-1=3\Rightarrow n=2\)
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Bài 5: Lũy thừa của một số hữu tỉ
Các câu hỏi tương tự
\(\dfrac{\left(\dfrac{-5}{7}\right)^n}{\left(\dfrac{-5}{7}\right)^{n-1}}\left(n\ge1\right)\) Tính
b) \(\dfrac{\left(-\dfrac{1}{2}\right)^{2n}}{\left(-\dfrac{1}{2}\right)^n}\left(n\in N\right)\)
bài 1 tính
a/ \(\left|1\dfrac{1}{2}-2\dfrac{1}{3}\right|^2+\left|1-\dfrac{5}{4}\right|\)
b/\(\left|\left(-1\right)^{100}-2\dfrac{1}{3}\right|+\dfrac{5}{6}\)
c/\(\left|\left(\dfrac{2}{3}\right)^{-1}-\dfrac{7}{4}\right|-\dfrac{7}{4}\)
d/ \(\left|x-5\right|+\left|x-8\right|\) với 5 \< x>/
Tính
a) \(\left(-52\right)^3:13^3\)
b) \(\left(\dfrac{1}{2}\right)^{15}:\left(\dfrac{1}{4}\right)^6\)
c) \(\left(\dfrac{1}{9}\right)^{30}:\left(\dfrac{1}{3}\right)^{56}\)
d) \(\left(\dfrac{1}{8}\right)^5:\left(\dfrac{1}{16}\right)^3\)
1. Tính:
C= \(\left(\dfrac{1}{2^2-1}\right)\left(\dfrac{1}{3^2-1}\right)\left(\dfrac{1}{4^2-1}\right).....\left(\dfrac{1}{100^2-1}\right)\)
2. Tìm x:
\(\left(\dfrac{2}{5}\right)^x>\left(\dfrac{5}{2}\right)^{-3}.\left(\dfrac{-2}{5}\right)^2\)
Help me!!!
Viết các biểu thức sau dưới dạng lũy thừa
a) \(2^2.9.\dfrac{1}{54}.\left(\dfrac{4}{9}\right)^2\)
b) \(2^3.2^5.\left(\dfrac{3}{2}\right)^4\)
c) \(\dfrac{\left(\dfrac{1}{2}\right)^3.\dfrac{1}{2^2}.8}{\left(-2^3\right)^2.16}.\left(2^2\right)^3\)
Viết các biểu thức sau dưới dạng lũy thừa
a) \(2^2.9.\dfrac{1}{54}.\left(\dfrac{4}{9}\right)^2\)
b) \(2^3.2^5.\left(\dfrac{3}{2}\right)^4\)
c) \(\dfrac{\left(\dfrac{1}{2}\right)^3.\dfrac{1}{2^2}.8}{\left(-2^3\right)^2.16}.\left(2^2\right)^3\)
Mấy chế zô giải giùm tui câu này:
Cho \(A=\left(\dfrac{1}{2^2}-1\right)\left(\dfrac{1}{3^2}-1\right)\left(\dfrac{1}{4^2}-1\right).....\left(\dfrac{1}{2013^2}-1\right)\left(\dfrac{1}{2014^2}-1\right)\) và \(B=-\dfrac{1}{2}.\)
Hãy so sánh A và B.
Tìm \(x\in\mathbb{Q}\), biết rằng :
a) \(\left(x-\dfrac{1}{2}\right)^2=0\)
b) \(\left(x-2\right)^2=1\)
c) \(\left(2x-1\right)^3=-8\)
d) \(\left(x+\dfrac{1}{2}\right)^2=\dfrac{1}{16}\)
Tìm \(n\in\) N*, biết: \(2n\div\left(1+\dfrac{1}{1+2}+\dfrac{1}{1+2+3}+\dfrac{1}{1+2+3+4}+...+\dfrac{1}{1+2+3+4+...+n}\right)=2020\)