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

$\boxed{x = 4, -1}$

Steps

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 ：$\boxed{x = 4, -1}$