Question

Which of the following is the graph of f(x) = x2 + 3x − 4? graph of a quadratic function with a minimum at 2, negative 9 and x intercepts at negative 1 and 5 graph of a quadratic function with a minimum at 3, negative 4 and x intercepts at 1 and 5 graph of a quadratic function with a minimum at 2.5, negative 2.4 and x intercepts at 1 and 4 graph of a quadratic function with a minimum at negative 1.5, negative 6.2 and x intercepts at 1 and negative 4

Answer 1

x intercepts at -4 and 1,

with a minimum at (-1.5, -6.25)

Explanation:

(x + 4)(x - 1) = 0

x = -4, 1

min = -b/2a = -3/2(1) = x = -1.5

y = (-1.5)² + 3(-1.5) - 4 = -6.25

Answer 2

graph of a quadratic function with a minimum at negative 1.5, negative 6.2 and x intercepts at 1 and negative 4

Explanation:

The graph shows the minimum is (-1.5, -6.25) and the x-intercepts are a -4 and 1. This matches the last description.

__

The x-coordinates of the offered minima are all different, so it is sufficient to know that the axis of symmetry is the line ...

x = -b/(2a) = -3/(2(1)) = -1.5 . . . . . . . for quadratic f(x) = ax² +bx +c

This is the x-coordinate of the minimum.