Question

Find the x intercepts

Answer 1

for x-intercept, y=0

Explanation:

`y = - 4 {x}^(2) + 16x + 20 \\ 0 = - 4 {x}^(2) + 16x + 20 \\divide \: by \: - 4 \\ 0 = {x}^(2) - 4x - 5 \\ {x}^(2) - 4x - 5 = 0 \\ from \: quadratic \: equation \\ x = \frac{ - b± \sqrt{ {b}^(2) - 4ac} }{2a} \\ from \: the \: equation \\ a = 1 \: \: b = - 4 \: \: c = - 5 \\ =x = \frac{ -( - 4)± \sqrt{ {( - 4)}^(2) - (4 * 1 * - 5) } }{(2 * 1)} \\ x = ( 4± √(26) )/(2) \\ x = 2± √(26) \\ x = 2 + √(26) \: \: or \: \: 2 - √(26) \\ x = 7.1 \: or \: x = −3.1`

x-intercepts are (7.1, 0) and (-3.1, 0)