f(n) = n² + 20
f(1) = 1² + 20 = 21
f(2) = 2² + 20 = 24
f(3) = 3² + 20 = 29
f(4) = 4² + 20 = 36
f(5) = 5² + 20 = 45
f(6) = 6² + 20 = 56
a) first three terms
Answer: 21, 24, 29
b) how many < 50
f(5)=45, f(6)=56 so
Answer: 5
