Given #f(x) = x^2 - 4# and g(x) = 2x - 1 , how do you determine the value of (f + g)(3)?

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Answer 1 · 2017-04-14T14:06:48

See the entire solution process below:

#(f + g)(x) = f(x) + g(x) = (x^2 - 4) + (2x - 1)#

Therefore:

#(f + g)(x) = (x^2 - 4) + (2x - 1)#

To find #(f + g)(3)# we must substitute #color(red)(3)# for every occurrence of #color(red)(x)# in #(f + g)(x)#:

#(f + g)(color(red)(x)) = (color(red)(x)^2 - 4) + (2color(red)(x) - 1)# becomes:

#(f + g)(color(red)(3)) = (color(red)(3)^2 - 4) + ((2 * color(red)(3)) - 1)#

#(f + g)(color(red)(3)) = (9 - 4) + (6 - 1)#

#(f + g)(color(red)(3)) = 5 + 5#

#(f + g)(color(red)(3)) = 10#