Question

If the equation 2x2+bx+5=0 has no real solutions, which of the following must be true?​

Answer 1

There are no choices but in order to qudratic equation not to have real roots the discriminant must be negative.

• d = b² - 2*2*5 = b² - 20

If d < 0, we get:

• b² - 20 < 0
• b² < 20
• b < |√20|
• - √20 < b < √20

or

• -2√5 < b < 2√5

or

• b = (-2√5, 2√5)