Book Maths Puzzle Algebra

How do you fill in the blanks to these problems?
1. (x+5)(x+?)=x^2+8x+15

2. (y-?)(y+4)=y^2+3y-4

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Book Other Question

f(x)= - 2/3 (x+2)^2 +1 This is one of the problems. I have to tell whether the parabola is going upward or downward. Then idenify A,H,K and vertex and give a rough draft of the graph.
We just learned this and I have 36 problems to do. We are not to follow the books instructions but the above instructions instead. I am lost! Can you get me started. Thank you. Another problem is f(x)= x^2+3 Using completing the square what is x? x^2-14x+49 = 64