f(x) = x^2 + x +1. Find the sum of all values of z for which f(3z) = 7

Is it 3x^2 +3x + 1 = 7 so z = 1 and -2....so the answer is -1

also, in general say you have f(x) ....how does the graph change (domain range, intercepts, max, min) if you make it, for example:

f(-2x)

.5f(x)

f(x-2)

f(x)+2