Algebra help?

Question

can someone please show me how to get the answer to this problem?

If f(1)= -1 and f(n+1)= [f(n)]^2 - 3, find f(4).

Answer 1

so from f(1) = -1, you can find f(2) using the equation

f(1+1) = [-1]^2 - 3
f(2) = -2

then find f(3)
f(2+1) = [-2]^2 - 3
f(3) = 1

from this you can find f(4):
f(3+1) = [1]^2 - 3
f(4) = -1

you can also see the pattern of answer going -1, -2, 1, -1, ... so you can find f(5), f(6) ... without calculation

Answer 2

Figure out f(2). Then figure out f(3). Then f(4) will be easy too.