Answer:
y = 4·4^x
Step-by-step explanation:
We can write the exponential function in the form ...
y = a·b^x
The y-value for x=0 is 4, so that is the multiplier 'a' in our equation.
The ratio of values between x=1 and x=0 is 16/4 = 4, so that is the value of 'b' in the equation. The equation is ...
y = 4·4^x
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Additional comment
This could also be written ...
y = 4^(x+1)
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Consider the values for x=0 and x=1.
x=0: y = a·b^0 = a
x=1: y = a·b^1 = ab
Then the ratio of values is (ab)/(a) = b.
This is the fact that we used in the above working.
