Posted by **Hannah** on Monday, March 15, 2010 at 11:25pm.

1)find f(g(x))

f(x) = x^2 + 2x g(x) = 1/x

x^3 + 2x

Is this correct?

2) solve: 3^x-1 = 10

ln 3/ ln 10 = .264

Is this correct? I am not sure how to do these.

3) Solve: 3^x+2 - 4 = 12

- Pre-Cal -
**Reiny**, Monday, March 15, 2010 at 11:44pm
no to both answers

1. f(x) = x^2 + 2x , g(x) = 1/x

then

f(g(x)

= f(1/x)

= (1/x)^2 + 2(1/x) = 1/x^2 + 2/x or (1+2x)/x^2

2.

the way you typed it, ...

3^x - 1 = 10

3^x = 11

x = ln11/ln3 = 2.182658

If you meant to type

3^(x-1) = 10

then

x-1 = ln10/ln3

x = ln10/ln3 + 1

=3.0959

3. Again I don't think you meant what you typed

Was it 3^(x+2) - 4 = 12 ???

if so then ...

3^(x+2) = 16

x + 2 = ln16/ln3

x = ln16/ln3 - 2 = .5237

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