15. Solve the equation by graphing. *More than one answer may be correct; check all that apply. \[ \begin{array}{l} x^{2}-3 x-4=0 \\ x=? \end{array} \] 5 4 $-1$ $-3$ $-5$ 0

Step 1 ：Given the quadratic equation: \(x^2 - 3x - 4 = 0\)

Step 2 ：Using the quadratic formula: \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\)

Step 3 ：Substitute the values: a = 1, b = -3, c = -4

Step 4 ：Calculate the discriminant: \(b^2 - 4ac = (-3)^2 - 4(1)(-4) = 25\)

Step 5 ：Find the roots: \(x = \frac{3 \pm \sqrt{25}}{2}\)

Step 6 ：Calculate the roots: \(x = \frac{3 + 5}{2} = 4\) and \(x = \frac{3 - 5}{2} = -1\)

Step 7 ：\(\boxed{x = 4, -1}\)