Question

What are the x-intercepts of the function f(x) = –2x2 – 3x + 20?

Answer 1

Function intercepts the x-axis where y=0


`f(x) = y = -2x^2 -3x +20 \\ 0 = -2x^2-3x+20 \\`

We can now calculate the discriminant and find the roots.


`\Delta = (-3)^2 - 4\cdot(-2)\cdot(20) = 169 \\\\ \sqrt\Delta = 13\\\\ x_1 = (-(-3) - 13)/(2\cdot(-2)) = (5)/(2) \\\\ x_2 = (-(-3) + 13)/(2\cdot(-2)) = 4`