y = a(x – h)² + k
So the vertex is (1, 4). this is (h, k)
y = a(x – 1)² + 4
now we solve for k by using the point it gives us and plugging 0 in for x and 1 in for y and solving
1 = a(0 – 1)² + 4 simplify
1 = a( -1)² + 4 square the -1
1 = a(1) + 4 no need for that 1 anymore
1 = a + 4 subtract 4 from each side
-3 = a
