Ta có:\(B=\dfrac{\left(-12\right)^5.27^4-32^2.81^4}{729^4:\left(-9\right)^4.16^5:\left(-8\right)^3}=\dfrac{\left(-3\right)^5.2^{10}.3^{12}-2^{10}.3^{16}}{3^{24}:3^8.2^{20}:\left(-2\right)^9}\\ =\dfrac{2^{10}.3^{16}.\left[-3-1\right]}{\left(-2\right)^{11}.3^{16}}=2\)

Vậy B = 2

Câu a) số lớn lắm

b) \(3^{-3}\cdot3^5\cdot3^x=3^8\)

=> \(\frac{1}{27}\cdot3^5\cdot3^x=3^8\)

=> \(\frac{1}{27}\cdot3^x=3^3\)

=> \(3^x=3^3:\frac{1}{27}=3^3:\left(\frac{1}{3}\right)^3=3^3:\frac{1^3}{3^3}=3^3\cdot3^3=3^6\)

=> x = 6

b) \(\left(7x+2\right)^{-1}=3^{-2}\)

=> \(\frac{1}{7x+2}=\frac{1}{9}\)

=> 7x + 2 = 9

=> 7x = 7

=> x = 1

Bài 2:

a) \(3^4\cdot\frac{1}{729}\cdot81^3\cdot\frac{1}{9^2}\)

\(=3^4\cdot\left(\frac{1}{3}\right)^6\cdot\left(3^4\right)^3\cdot\left(\frac{1}{3}\right)^4\)

\(=3^4\cdot\left(\frac{1}{3}\right)^6\cdot3^{12}\cdot\left(\frac{1}{3}\right)^4=3^{16}\cdot\left(\frac{1}{3}\right)^{10}=\frac{3^{16}}{3^{10}}=3^6\)

b) \(\left(8\cdot2^5\right):\left(2^4\cdot\frac{1}{32}\right)=\left(2^3\cdot2^5\right):\left(2^4\cdot\left(\frac{1}{2}\right)^5\right)\)

\(=2^8:\left(2^4\cdot\frac{1^5}{2^5}\right)=2^8:\left(\frac{2^4}{2^5}\right)=2^8:2^{-1}=512\)

c) \(12^8\cdot9^{12}=\left(2^2\cdot3\right)^8\cdot\left(3^2\right)^{12}=2^{16}\cdot3^8\cdot3^{24}=2^{16}\cdot3^{32}\)

d) Tương tự

Trả lời rõ cho mik có đc k mn

bai de the ma cung hoi