Find the Discriminant -3x^2-9x-7=0

$- 3 x^{2} - 9 x - 7 = 0$

Step 1

The discriminant of a quadratic is the expression inside the radical of the quadratic formula.

$b^{2} - 4 (a c)$

Step 2

Substitute in the values of $a$ , $b$ , and $c$ .

${(- 9)}^{2} - 4 (- 3 \cdot - 7)$

Step 3

Evaluate the result to find the discriminant.

Simplify each term.

Raise $- 9$ to the power of $2$ .

$81 - 4 (- 3 \cdot - 7)$

Multiply $- 4 (- 3 \cdot - 7)$ .

Multiply $- 3$ by $- 7$ .

$81 - 4 \cdot 21$

Multiply $- 4$ by $21$ .

$81 - 84$

Subtract $84$ from $81$ .

$- 3$