Question

the exponential function f(x) =5^x after a vertical stretch by a factor of 3 and a reflection across the y axis

Answer 1

$f(x)=5^x$

after a vertical stretch by a factor of 3:

$f(x)=5^{3x}$

And after a reflection across the y-axis:

$f(x)=5^{-3x}$