Don B. answered 12/12/22
Patient and Creative Tutor Makes Math & Music Theory Interesting
The problem is to find a and h. The graph passes through (10. -5), so we can plug those numbers into the function:
-5 = a(10 - h)^2
The graph passes through (5, 0), so
0 = a(5 - h)^2
The key to finding a and h is the Zero Factor Theorem: If the product of two expressions is 0, at least one of the expressions must be 0. So, from the 2nd equation, either a is 0, or (5-h)^2 is. If a was 0, the function value y would _always_ be 0, so the graph couldn't pass through (10, -5) and the 1st equation couldn't be correct. Therefore (5-h)^2 is 0, which means h = 5. We can fill that in in the first equation:
-5 = a(10 - 5)^2
Solving that gives a = -1/5.
Therefore the quadratic function is y = -1/5(x - 5)^2.