Question

is y=0.3x a exponential decay function

Answer 1

try it yourself.. draw a graph.. calculate few values of y for given value of x...

For instance.. y = 0.3x

1. x=10 y is 3
2. x=20 y is 6

and few more values... Then draw a graph..

Answer 2

?? Can you continue from where i have stopped ?

Answer 3

\(\large\color{black}{ y=ab^x }\) is an exponential function:
We know that: \(\large\color{black}{ b^0 }\) just like any number raise to the zero (asides from \(\large\color{black}{ 0^0 }\) ) is equal to \(\large\color{black}{1 }\).
normally when x=0, then b^x is 1, and therefore the y-intercept is "a"

your case is just: \(\large\color{black}{ y=b^x }\) (without "a")
you know that when x is 1 you multiply times 0.3 once (saying it is just 0.3)
and when x is 2 you multiply 0.3 twice, saying it is \(\large\color{black}{ 0.3 \times 0.3 }\) which is equivalent to 0.09.
and so on.