# How do use the discriminant to find all values of b for which the equation #x^2-bx+4=0# has one real root?

##### 3 Answers

#### Explanation:

The discriminant of a quadratic is

In this case,

Equal roots means

#### Explanation:

For the Qudr. Eqn. **One Root,** or, to

have **Two Identical Roots,**

In our case,

Incidentally, if

In

#### Explanation:

Given the standard form

where

For there to only be 1 real root we need the form

This means that

Multiply both sides by

square root both sides

But