4. 5^(3x) = 900 take the log of both sides
log 5^(3x) = log 900
3x * log (5) = log (900)
x = log (900) / [ 3 * log (5) ] ≈ 1.41
5. f =x^2 + 5 g = [ x + 5 ] / x f ° g (-3) = f [ g(-3) ]
g(-3) = [ -3 + 5 ] / -3 = -2/3
f (-2/3) = (-2/3)^2 + 5 = 5 + 4/9 = 49 / 9
