# Question: Quadratic Formula Assignment Producing -nan

Hi everyone. I’m trying to complete the Quadratic Formula assignment but my print statements are producing the wrong output.

Instead of producing a number I get `-nan`.

Here’s my code and a screenshot:

``````var a: Double = 2.0
var b: Double = 5.0
var c: Double = 3.0

var root1: Double = 0
root1 = (b * 2) - 4 * (a * c)
var root2: Double = (b * 2) - 4 * (a * c)

//no -nan
print(root1)

// produces -nan
root1 = root1.squareRoot()
root2 = root2.squareRoot()

// troubleshooting
print(root1)

root1 = -b + root1
root1 = root1 / (2 * a)

root2 =  -b - root2
root2 = root2 / (2 * a)

print(root1)
print(root2)
``````

In the discriminant (the expression underneath the square root),    `b` has an exponent of `2`.

Exponentiation means:

In your screenshot, you have interpreted exponentiation of `b` to the power `2` as multiplication by `2`,

``````// You wrote:
(b * 2) - 4 * (a * c)

// It should be:
(b * b) - 4 * (a * c)
``````

Alternatively, you could use the `pow` function (whose first argument is the base and the second argument is the exponent),

``````import Foundation

(pow(b, 2)) - 4 * (a * c)
``````
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Thank you so much. Obviously, my math skills are not too strong.