Question

Consider the functions f(x) = 2(x − 7) and g(x) = 2x. What is the value of (f + g)(4)?

−6

14

2

−2

Answer 1

(f+g)(x)=f(x)+g(x)

Hence,
(f+g)(4)=f(4)+g(4)

Now,
f(4)=2(4-7)
=>f(4)=-6
g(4)=2x4
=>g(4)=8

So,
(f+g)(4)=f(4)+g(4)
=>(f+g)(4)=-6+8
=>(f+g)(4)=2

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http://www.purplemath.com/modules/fcnops.htm