What is the discriminant of x^2 + 5x + 7 = 0 and what does that mean?

1 Answer
Meave60
Jul 27, 2015

The discriminant is -3, which means there are two complex roots.

Explanation:

x^2+5x+7=0 is a quadratic equation. The general form of a quadratic equation is a^2+bx+c, where a=1, b=5, and c=7.
The discriminant, "D", comes from the quadratic formula in which x=(-b+-sqrt(color(red)(b^2-4ac)))/(2a) .

"D"=b^2-4ac =

"D"=5^2-4(1)(7) =

"D"=25-28 =

"D"=-3

A negative discriminant means there are two complex roots (x-intercepts).

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