# [SOLVED] (f o h)(x)

• January 27th 2009, 11:43 PM
moonman
[SOLVED] (f o h)(x)
f(x) = x^2 + 4
h(x) = 2x - 1/ x + 3

Find (f o h)(x)

(f o h)(x) = f(h(x))

f(2x-1 / x +3) = (2x-1 / x +3)^2 + 4

f(2x-1 / x +3) = (4x^2 - 4x + 1 / x^2 + 6x +9 ) + 4

Did I do this correctly?(Tmi)
• January 27th 2009, 11:54 PM
Moo
Hello,
Quote:

Originally Posted by moonman
f(x) = x^2 + 4
h(x) = 2x - 1/ x + 3

Find (f o h)(x)

(f o h)(x) = f(h(x))

f(2x-1 / x +3) = (2x-1 / x +3)^2 + 4

f(2x-1 / x +3) = (4x^2 - 4x + 1 / x^2 + 6x +9 ) + 4

Did I do this correctly?(Tmi)

Yes :)

But you can also put 4 in the fraction :

$\frac{4x^2-4x+1}{x^2+6x+9}+4=\frac{4x^2-4x+1+4(x^2+6x+9)}{x^2+6x+9}$
and then expand
• January 28th 2009, 12:02 AM
moonman
Quote:

Originally Posted by Moo
Hello,

Yes :)

But you can also put 4 in the fraction :

$\frac{4x^2-4x+1}{x^2+6x+9}+4=\frac{4x^2-4x+1+4(x^2+6x+9)}{x^2+6x+9}$
and then expand

(Clapping) ahh! Thank you