Question

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Answer 1

For x = 4, then it means 3 to the fourth power or 3 times 3 times 3 times 3 times 3.  3^4 = 81 and 8 times that is 648.

y(x) = 8 * 3^x where x = 4:

y(x) = 8 * 3^4 = 8 * 81
y(x) = 648

The Function Rule then being that for every value of x there is one and only one value of y. y is the dependent variable and x is the independent variable.