the graph of your equations looks like the following:
the straight line is y = 3x
the line that looks like the letter u is y = 3x^2
that's a quadratic equation.
the line that looks like it goes from 0 all the way to the left to a very high number all the way to the right is y = 3^x
that's an exponential equation.
a table of values from -5 to 5 would look like this:
x y = 3x y = 3x^2 y = 3^x
-5 -15 75 .004115226 = 3^(-5) = 1/3^5 = 1/243
-4 -12 48 .012345679 = 3^(-4) = 1/3^4 = 1/81
-3 -9 27 .037037037 = 3^(-3) = 1/3^3 = 1/27
-2 -6 12 .111111111 = 3^(-2) = 1/3^2 = 1/9
-1 -3 3 .333333333 = 3^(-1) = 1/3 = 1/3
0 0 0 1
1 3 3 3
2 6 12 9
3 9 27 27
4 12 48 81
5 15 75 243