exam Maths Puzzle Numerical Ability

i don't know how to solve this problem.

directions: find the first three output values for each function. Use z=0 for the first input value.

Question #1:

f(z)=z^2=2i

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exam Other Question

Evaluate
f(x)=3x^2-4x-3 at f(x-1)

am i posting this question in the right place?
How would you use a histogram to chart residuals? What would this tell you?