Question

At what points does the graph of f(x)=2x^2-4x-16 intersect the x-axis

Answer 1

y = 2x² - 4x - 16
or
2x² - 4x - 16 = y

A graph intersects x-axis if coordinate y is equal 0, substitute 0 to y
2x² - 4x - 16 = 0
divide both side by 2
x² - 2x - 8 = 0
factorize the algebraic expression
(x - 4)(x + 2) = 0

x = 4 or x = -2

The graph intersects x-axis at (4,0) and (-2,0)

Answer 2

At points (4,0) and (-2,0), the graph of f(x)=2x^2-4x-16 intersect the x-axis.

Hope this helps.