Math quadratics vertex form?

[coco]

Convert C = 0.06t^2 - 0.27t + 5.36 into vertex form.

The axis of symmetry is 2.25 but I keep getting a different answer.

Help and please clarify.

[Jesse_J]

Vertex form: y = a(x - h)^2 + k, where (h, k) is the vertex and the equation of the axis of symmetry is x = h

C = 0.06t^2 - 0.27t + 5.36 (group the first two terms together)
C = (0.06t^2 - 0.27t) + 5.36 (factor out 0.06 from the group)
C = 0.06(t^2 - 4.5t) + 5.36 (take half of -4.5, which is -2.25, and square it to 5.0625; add it inside the group; multiply it by 0.06, which is 0.30375 and subtract this outside the group)
C = 0.06(t^2 - 4.5t + 5.0625) + 5.36 - 0.30375 (factor the group)
C = 0.06(t - 2.25)^2 + 5.36 - 0.30375 (subtract)
C = 0.06(t - 2.25)^2 + 5.05625

The vertex is (2.25, 5.05625) and the axis of symmetry is x = 2.25.