the first, (f+g)(x) is f(x) + g(x)
calculating it like:
x² + 7x + (8 -x²)
= x² + 7x + 8 -x²
= 7x + 8
you just writ it down as a calculation and calculate it. i hope that helps understanding the concept/basic idea. please let me know wich ones you need more help with.
edit1: the domain is the range of possibilities wich x we can plug into the new equation
