
functions problem
I have a few problems I would be VERY thankful to have some help with. Thank you in advance!
1. Determine whether the pair is parallel, perpendicular, or neither.
6x+2y=8
18x+6y=25
2. Find the given value.
Find (f*g)(2) when f(x)=x+1 and g(x)= 3x^2 +15x5
3. Find the domain of the composite function f*g
f(x) = x+3, g(x) = 2/ x+6
4. Determine whether the given function is onetoone. If so, find it's inverse.
f(x)= 4x20
Thanks again for anyone's help!!!

1. Solve for y in each equation, then inspect the slope of the two lines:
 If they are the same, then they are parallel
 If their product is 1, then they are perpendicular
 If they are not equal and their product is not 1, then they are neither parallel nor perpendicular.
2. Note that $\displaystyle (f \cdot g)(x) = f(x) g(x)$
Plug in $\displaystyle x = 2$ in $\displaystyle f(x)$ and $\displaystyle g(x)$, then find their products.
3. $\displaystyle (f \circ g)(x) = f(g(x)) = \left(\frac{2}{x+6}\right)+3$
The domain is the set of real numbers for which the composite function is defined. The function is defined for all x such that $\displaystyle x+6 \neq 0 \implies x \neq 6$
4. It's a linear function, so it is injective. To check, graph the function and apply the horizontal line test (If the horizontal lines intersect the curve at most one point, then it is onetoone. Otherwise, it's not injective.)