What is the axis of symmetry of the quadratic function y = 2(x + 3)2 + 5?

The function is in vertex form, y = a(x − h)² + k, whose axis of symmetry is x = h. Here, (x + 3)² = (x − (−3))², so h = −3. Therefore, the axis of symmetry is x = −3, choice B.

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