\(\dfrac{3}{2}-\left(x-2\dfrac{1}{3}\right)=\dfrac{-3}{4}-1\dfrac{1}{8}\\ \Rightarrow\dfrac{3}{2}-x+\dfrac{7}{3}=\dfrac{-3}{4}-\dfrac{9}{8}\\ \Rightarrow\dfrac{23}{6}-x=-\dfrac{15}{8}\\ \Rightarrow x=\dfrac{23}{6}-\left(-\dfrac{15}{8}\right)\\ \Rightarrow x=\dfrac{137}{24}\)

\(\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}+\dfrac{5}{7}=9\dfrac{5}{7}\\ \Rightarrow\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}=9\dfrac{5}{7}-\dfrac{5}{7}\\ \Rightarrow\left(x-\dfrac{1}{2}\right):\dfrac{1}{3}=9\\ \Rightarrow x-\dfrac{1}{2}=9.\dfrac{1}{3}\\ \Rightarrow x-\dfrac{1}{2}=3\\ \Rightarrow x=3+\dfrac{1}{2}\\ \Rightarrow x=\dfrac{7}{2}\)

\(a/5.3^{x+3}-14=121\\ \Rightarrow5.3^{x+3}=135\\ \Rightarrow3^{x+3}=135:5=27\\ \Rightarrow3^{x+3}=3^3\\ \Rightarrow x+3=3\\ \Rightarrow x=0\)

\(b/4^x=4.4^{10}-3.4^{10}\\ \Rightarrow4^x=\left(4-3\right).4^{10}\\ \Rightarrow4^x=4^{10}\\ \Rightarrow x=10\)

\(\left(x+5\right)^3.\left(2x\right)^3=\left[2x\left(x+5\right)\right]^3\\ =\left(2x^2+10x\right)^3\)

Nhận thấy: \(5^{27}=\left(5^3\right)^9=125^9< 128^9=\left(2^7\right)^9=2^{63}\left(1\right)\)

và: \(2^{63}=\left(2^9\right)^7=512^7< 625^7=\left(5^4\right)^7=5^{28}\left(2\right)\)

\(\underrightarrow{\left(1\right);\left(2\right)}5^{27}< 2^{63}< 5^{28}\)

\(3^{39}< 3^{40}=\left(3^2\right)^{20}=9^{20}< 11^{20}< 11^{21}\)

\(27x^3-108x^2+144x-64\\ =\left(3x\right)^3-3.\left(3x\right)^2.4+3.3x.4^2-4^3\\ =\left(3x-4\right)^3\)

Cạnh hình vuông:

  416 x 2 = 832 (cm)

Chu vi HV mới tạo thành:

  832 x 4 = 3328 (cm)

  Đ/S:3328cm

Đáp án D bạn nhé

a) \(\dfrac{1}{2}\times\dfrac{2}{5}=\dfrac{1}{5}\)

b) \(25\%=\dfrac{25}{100}=\dfrac{1}{4}\)

c) 45,7

d) 120 + 15 = 135