Mathematics

Mathematics

Problem

The focus of the parabola x2−8x+2y+7=0x^2 - 8x + 2y + 7 = 0 is a. (0,−12)\left(0, -\frac{1}{2}\right) b. (4,4)(4, 4) c. (4,92)\left(4, \frac{9}{2}\right) d. (−4,−92)\left(-4, -\frac{9}{2}\right)
Intuitive explanation

Rewrite the parabola in standard form by completing the square—this transforms a messy equation into the canonical (x−h)2=4p(y−k)(x-h)^2 = 4p(y-k) shape. Once you identify the vertex (h,k)(h, k) and the focal parameter pp (which tells you how far the focus sits from the vertex along the axis of symmetry), finding the focus is just one step: it's always at distance ∣p∣|p| from the vertex in the direction the parabola opens.

Intuitive explanation

Rewrite the parabola in standard form by completing the square—this transforms a messy equation into the canonical (x−h)2=4p(y−k)(x-h)^2 = 4p(y-k) shape. Once you identify the vertex (h,k)(h, k) and the focal parameter pp (which tells you how far the focus sits from the vertex along the axis of symmetry), finding the focus is just one step: it's always at distance ∣p∣|p| from the vertex in the direction the parabola opens.

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