Mathematics

# Find x if f(x) = 2x 7 and f(x) = -1.

$f(x)=2x^7=-1\\ ==\ \textgreater \ x= \sqrt7]{ -\frac{1}{2}} \\ ==\ \textgreater \ x=-\sqrt7]{-\frac{1}{2}}\\ ==\ \textgreater \ x=0,9057236642639066715941728732151...\\.$