If #f(x) = 2x - 10# ; #g (x) = 4x + 20# what is the value of (f + g) (3) ?

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Answer 1 · 2015-10-29T11:09:48

#(f+g)(3) = 28#

First method:

Add #f(x) + g(x)#

#(2x-10)+(4x+20)#

Combine like terms.

#=6x+10#

Then substitute #3# for #x#.

#=6(3)+10#
#=18+10#
#=28#

Second method:

Substitute #3# into both functions individually.

#f(3)= 2(3)-10#
#=6-10#
#=-4#

#g(3) = 4(3)+20#
#=12+20#
#=32#

Then add the answers you get from substituting together.

#=-4+32#
#=28#