For which values of c does the following polynomial have two complex roots? x^2+4x+c

For this case we have that by definition, the discriminant of a quadratic expression is given by:

If the discriminant is less than zero then the expression has two different complex roots.

In this case we have the following expression:

So we have to:

The discriminant is given by:

Then, if we want two complex roots it must be fulfilled that:

Thus, the expression has two complex roots for all values greater than 4.

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times both sides by 2, times () by 8, add alile terms, move terms, add alike and caculate divide both sides by 3

b. 2 and 4

step-by-step explanation: