NECO 2023 · Paper 1 · Q28

Find the focus and directrix of the parabola $y^2 = 64x$ .

Worked solution (try it first)

Compare $y^2 = 64x$ with the standard form $y^2 = 4ax$ : $4a = 64$ , so $a = 16$ .
The focus is $(a, 0) = (16, 0)$ and the directrix is the line $x = -a$ , that is $x = -16$ , option C.