Question

pls. help...
The functions f and g satisfy
f(x) + g(x) = 3x + 5
f(x) - g(x) = 5x + 7
for all values of x. Determine the value of 2f(2)g(2).

Answer 1

First, find f and g.
from the 2nd equation, we see that g = f - 5x - 7
plug that into the first equation and you get

f + (f - 5x - 7) = 3x+5
f = 4x+6
so
g = -x-1

Now you can evaluate f(2) and g(2)