Answer:
the answer is in fact 7/2
The answer is A(45) = -211
I am going to explain this using the substitution method, considering it appears to be the best in this situation.
We know (from the bottom equation) that y can equal 3x+20. Using this knowledge, we substitute the y in the top equation for 3x+20. Now, we have an equation that looks like this:
3x+20=x^2+2x
Now we need to move x to one side and then do some radicals (square roots).
Subtract the 2x on the right (since it is smaller, negatives = NONONO), which will give you
x+20=x^2
Now, we take the square root of both sides to get
rad(x+20)=x
Now we have to simplify. 20 doesn't have a square root, but 4 goes into 20, and 4 has a square root of 2. This now becomes
2rad(x+5)
This doesn't simplify any further... we have a problem... no way to isolate x as far as my knowledge goes... Sorry, can't help you any further than that, but another person or your teacher might be able to. R.I.P...
The number in parenthesis after f is the x coordinate. Basically, it says which y coordinate is tied with an x value. In choice a, it says that when x is 0 y is 3, etc.
So, you can look at the graph to see which answer choice has a point from the graph. Choice a says (0,3), and that does not match. Choice b says (5,-1) and that does match. So the answer is B.
*(x,y)*
