PDA

View Full Version : Quadratic Function: xSqared - 3x - 10 = 0



Melanie953
05-26-2009, 04:17 PM
The Question I have is xSqared - 3x - 10 = 0
Please Please Please help me i have no clue how to do it!
Thank you :D

Subhotosh Khan
05-26-2009, 04:23 PM
The Question I have is xSqared - 3x - 10 = 0
Please Please Please help me i have no clue how to do it!
Thank you :D

Then why are you even trying to do this problem?

For a refresher to:

http://www.purplemath.com/modules/solvquad.htm

mathpedia
05-27-2009, 02:28 AM
The Question I have is xSqared - 3x - 10 = 0
Please Please Please help me i have no clue how to do it!
Thank you :D

When you have an expression that contains a square root, the best way to solve it, is to separate the square root from the other terms, and then raise the expression to the 2nd power. Of course, first you the condition the term under the square root, to be greater or equal to 0:

x \geq 0

\sqrt{x} - 3*x - 10 = 0 <=> \sqrt{x} = 3*x + 10 <=> x = (3*x + 10)^2 <=> x = (9*x)^2 + 60*x + 100 <=>
( 81*x^2 + 59*x + 100 = 0. From the formula of quadratic equation, we get:x1,2 = \frac{(-59 \pm \sqrt{59*59 - 4*81*100})}{2*81}. Because \sqrt{59*59 - 4*81*100})} < 0 => We have no real solution for your equation.

Denis
05-27-2009, 06:22 AM
The equation is x^2 - 3x - 10 = 0 : NO square root.
(x - 5)(x + 2) = 0

I see from your link that you charge $30 an hour.