Question

e.(-3/4)^3x-1=256/81

f.172x²-7⁹:98³=2^-3

Answer 1

e) 

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

\(\left(-\frac{3}{4}\right)^{3x}=\left(-\frac{4}{3}\right)^4\)

\(\left(-\frac{3}{4}\right)^{3x}=\left(-\frac{3}{4}\right)^{-4}\)

\(3x=-4\)

\(x=-\frac{4}{3}\)

f) \(172x^2-7^9:98^3=2^{-3}\)

\(172x^2-\frac{7^9}{\left(7^2.2\right)^3}=\frac{1}{2^3}\)

\(172x^2-\frac{7^3}{2^3}=\frac{1}{2^3}\)

\(172x^2=\frac{7^3}{2^3}+\frac{1}{2^3}=\frac{344}{8}\)

\(x^2=\frac{344}{8}:172=\frac{1}{4}\)

x=1/2 hoặc x=-1/2