Which is the equation of the axis of symmetry of the graph of y = –3(x – 6)2 + 5?

In vertex form, y = a(x − h)² + k, the axis of symmetry is x = h. Here the squared term is (x − 6)², so h = 6 and the axis is x = 6. Therefore, the correct choice is D, x = 6.

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