Question

If f(x) = 2x2 + 1 and g(x) = x2 – 7, find (f + g)(x).
A. 3x2 + 8
B. 3x2 – 6
C. x2 – 6
D. x2 + 8

Answer 1

Remember that, although it may look intimidating, (f+g)(x) is simply f(x) + g(x)
Therefore:
(f+g)(x) = f(x) + g(x)             Substitute the functions for f(x) and g(x)
(f+g)(x) = (2x² + 1 )+ (x² - 7)         
Notice that we first want to write the functions in as parenthesis before we add them. This helps us keep from getting confused on what signs to give each term.
(f+ g)(x) = 2x² + x² + 1 - 7    Collect like terms
(f + g) (x) = 3x² - 6
Answer is B