1.) find g of f(x) if f(x)= x^2 + 3x and g(x)= 2x -1 2.) b= log^3 7?

Question:logarithms

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Answers:
for the first part:
to find g of f(x), just substitute the whole expression of f(x) in place of x in g(x), thus giving you - 2x^2+6x-1

for the second part, I'm assuming you mean find log 3 base 7:
in which case, the answer is given by (log 3 base 10)/(log 7 base 10).
the rule here is log a base b = (log a base c)/(log b base c), where c can be any base you are comfortable with

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im lost

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1) if you mean...

g(f(x)) = 2(x^2 + 3x) - 1 = 2x^2 + 6x - 1 or
f(g(x)) = (2x - 1)^2 + 3(2x - 1) = 4x^2 - 4x + 1 + 6x - 3 =
4x^2 + 2x - 2

2) 3^b = 7 so just solve for b.

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