The functions are .
a) (f + g)(x)
\ (Substitute
)
.
b) (f g)(x)
(Substitute
)
Product of same sings is positive.
\.
c)
(Substitute
)
(Using FOIL method)
Product of difference sings is negative.
\Product of same sings is positive.
\.
d)
(Substitute
)
Take out common factor.
\.
The functions are ,
,
and
.