Question

Tìm x, biết : 

a. \(3x^2-51=-24\)

b. \(5^x.\left(5^3\right)^2=625\)

c. \(\left(\frac{-3}{4}\right)^{3x-1}=\frac{256}{81}\)

Answer 1

a.\(3x^2-51=-24\)

\(\Rightarrow3x^2=27\)

\(\Rightarrow x^2=9\)

\(\Rightarrow x=3\)

Answer 2

b.\(5x.\left(5^3\right)^2=625\)

\(\Rightarrow5x=5^5:5^{\left(3x2\right)}\)

\(\Rightarrow5x=5^5:5^6\)

\(\Rightarrow5x=5^{-1}=0,2\)

\(\Rightarrow x=0,2:5\)

\(\Rightarrow x=0,04\)

Answer 3

Mk làm lộn câu b nha.

Answer 4

b\(5x.\left(5^3\right)^2=625\)

\(5x.5^6=5^4\)

\(5x=5^{-2}\)

\(5x=0,04\)

\(x=0,008\)