The vertex of a quadratic function is (6, 2), and the y-intercept of the function is (0, −70). The equation of the function in vertex form, f(x)=a(x−h)2+k, is shown.−70=a(0−6)2+2

Substitute the vertex (6, 2) into vertex form to get f(x) = a(x − 6)² + 2. Using the y-intercept (0, −70), −70 = a(0 − 6)² + 2 = 36a + 2, so 36a = −72 and a = −2. The correct choice is −2.

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