Question #N147
The equation $x^2 - 2x - 9 = 0$ can be solved using the quadratic formula. What is the value of the discriminant for this equation?
A. 40
B. 32
C. 16
D. 4
Correct Answer is: A
The quadratic formula is used to solve equations in the form $ax^2 + bx + c = 0$, where $a$, $b$, and $c$ are constants. The discriminant of this equation is $b^2 - 4ac$. In the given equation, $a = 1$, $b = -2$, and $c = -9$. Therefore, the discriminant is $(-2)^2 - 4(1)(-9) = 4 + 36 = 40$.