Let f(x)=#x^2+4# and g(x)=2x-2, evaluate the following?

Question

Ask for:
a). 3f(x)+3g(x)
b).g(f(4))

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Answer 1 · 2018-02-22T06:12:44

Please refer to the explanation below.

#a).# Find #3f(x)+3g(x)#

We first need to find #3f(x)#.

So, that is basically #3# multiplied by the function #f(x)#, and therefore will be

#3(x^2+4)=3x^2+12#

Same goes for #3g(x)#.

It becomes #3(2x-2)=6x-6#.

Therefore, #3f(x)+3g(x)=3x^2+12+6x-6#

#=3x^2+6x+6#

#b).# Find #g(f(4))#

Here, we need to find #f(4)# first.

We got: #f(x)=x^2+4#

#:.f(4)=4^2+4#

#=20#

#:.g(f(4))=g(20)#

We got: #g(x)=2x-2#

#:.g(20)=40-2#

#=38#

#:.g(f(4))=38#