Biểu thức 7 div 3 có giá trị là:
A. 2
B. 1
C. 0
D. 7
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\(2-\dfrac{7}{4}:\left(\dfrac{3}{4}+1\right)\\ =2-\dfrac{7}{4}:\dfrac{7}{4}=2-1\\ =1\\ Chọn.C\)
A=\(2^2-9^3+4^{-2}.16-2.5^2\)
\(=4-729+1-50=-774\)
B=\(\left(2^3.2\right).\dfrac{1}{2}+3^{-2}.3^2-7.1+5\)
\(B=2^4.\dfrac{1}{2}+1-7+5=8+1-7+5=7\)
C = 2-3 + (52)3.5-3 + 4-3.16 - 2.32 - 105.(\(\dfrac{24}{51}\))0
C = \(\dfrac{1}{8}\) + 56.5-3 + 4-3.42 - 2.9 - 105.1
C = \(\dfrac{1}{8}\) + 53 + \(\dfrac{1}{4}\) - 18 - 105
C = (\(\dfrac{1}{8}\) + \(\dfrac{1}{4}\)) - (105 - 125 + 18)
C = \(\dfrac{3}{8}\) - (-20 + 18)
C = \(\dfrac{3}{8}\) + 2
C = \(\dfrac{19}{8}\)
\(A=2^0+2^1+2^2+...+2^{21}\)
\(2A=2^1+2^2+2^3+...+2^{22}\)
\(2A-A=\left(2^1+2^2+2^3+...+2^{22}\right)-\left(2^0+2^1+2^2+...+2^{21}\right)\)
\(A=2^{22}-1\)
\(2^{22}-1=2^{2n}-1\)
\(2^{2\times11}-1=2^{2n}-1\)
n = 11
a)
\(\left(\dfrac{1}{2}\right)^3\times\left(\dfrac{1}{2}\right)^2\)
\(=\left(\dfrac{1}{2}\right)^{3+2}\)
\(=\left(\dfrac{1}{2}\right)^5\)
\(=\dfrac{1}{32}\)
b)
\(\left(-\dfrac{2}{3}\right)^7:\left(-\dfrac{2}{3}\right)^5\)
\(=\left(-\dfrac{2}{3}\right)^{7-5}\)
\(=\left(-\dfrac{2}{3}\right)^2\)
\(=\dfrac{4}{9}\)
c)
\(\left[\left(\dfrac{2}{5}\right)\right]^0=1\)
Đáp án đúng : A