X is equal to 19. Hoped this helped
1/9
Here's the proper explanation:
Since the vertex is (2,-1), the original equation will look like this: y=a*(x-2)^2-1
When the substitution happens we get to this:
0=a*(5-2)^2-1 then 1=a*(5-2)^2 -> 1=a*9
So, a=1/9! Written in another form:
1/9x^2-4/9x+4/9-1
Hope could help :)
