Question

a, \(\left(-0,4\right)^x=\dfrac{16}{625}\)

\(b,\left(\dfrac{-2}{3}\right)^x.\left(\dfrac{-2}{3}\right)=\dfrac{-32}{243}\)

\(c,\left(5x+1\right)^2=\dfrac{36}{49}\)

Answer 1

a: \(\Leftrightarrow\left(-\dfrac{2}{5}\right)^x=\left(-\dfrac{2}{5}\right)^x\)

=>x=4

b: \(\Leftrightarrow\left(-\dfrac{2}{3}\right)^{x+1}=\left(-\dfrac{2}{3}\right)^5\)

=>x+1=5

=>x=4

c: =>5x+1=6/7 hoặc 5x+1=-6/7

=>5x=-1/7 hoặc 5x=-13/7

=>x=-1/35 hoặc x=-13/35