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

Answer

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Answer

$x = 4, - 1$

Steps

Step 1 ：Given the quadratic equation: $x^{2} - 3 x - 4 = 0$

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

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

Step 4 ：Calculate the discriminant: $b^{2} - 4 a c = (- 3)^{2} - 4 (1) (- 4) = 25$

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 ： $x = 4, - 1$