Can someone confirm my work? f(x) = 4x2 − 7x − 15 part a finding x-intercepts: f(x) = 4x^2 − 7x − 15 0 = 4x^2 − 7x − 15 a = 4, b = -7, c= -15 a * c = -60 -12 * 5 = -60 -12 + 5 = -7 (4x + 5)(4x -12) 4x^2 - 12x | + 5x -15 4x(x - 3) + 5(x - 3) (x - 3)(4x +5) x = 3 x = -1.25 or -5/4 part b finding vertex: minimum point (x1 + x2)/2 (3 -1.25)/2 = 0.875 f(x) = 4x^2 − 7x − 15 f(0.875) = 4(0.875)^2 − 7(0.875) − 15 f(0.875) = 3.06 - 6.125 - 15 f(0.875) = -18.065 vertex = (0.875, -18.065)