X*X + 20*X - 2400 = 0 can be factored to:

( X + 60 ) * ( X - 40 ) = 0

So X = 40 or X = -60

Bill

>Now I'm really confused because I know X=40 so...?
>
>>>How do you solve for x in the equation X*(X+20)=2400
>>>
>>>Thanks
>>>Jon
>>
>>X*(X+20)=2400
>>X*X + 20*X = 2400
>>X*X + 20*X - 2400 = 0
>>And that is a typical Quadratic equation :-)
>>
>>http://en.wikipedia.org/wiki/Quadratic_equation