SOLUTION: how can i solve X squared - 4X - 2. i have failed to find factors of 2X squared that will result in 4X. e.g. this is what i tried. X squared times -2 i get -2Xsquared but t

Algebra ->  Quadratic Equations and Parabolas -> SOLUTION: how can i solve X squared - 4X - 2. i have failed to find factors of 2X squared that will result in 4X. e.g. this is what i tried. X squared times -2 i get -2Xsquared but t      Log On


   

Question 1003958: how can i solve X squared - 4X - 2. i have failed to find factors of 2X squared that will result in 4X.
e.g. this is what i tried.
X squared times -2 i get -2Xsquared
but the factors i am getting are not resulting into 4X when i add or subtract them
please help
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
your equation is x^2 - 4x - 2

you are looking for factors that add to or subtract from each other to get -4.

you multiply the coefficient of the x^2 term by the constant term to get 2.

factors of 2 are 1 * 2 or 2 * 1.

neither one of these factors will add to or subtract from each other to get -4.

that means you can't factor this equation directly.

you will need to use the quadratic formula.

put your equation in quadratic form to get:

x^2 - 4x + 2 = 0

standard form is ax^2 + bx + c = 0

that means that:

a = 1
b = -4
c = -2

use the quadratic formula shown below to solve for x. 


             x    =        -b plus or minus sqrt(b^2 - 4ac)
                          ----------------------------------
                                        2a


you will get:

x = -.449 or x = 4.449 rounded to 3 decimal places.

the graph of this equation confirms the solution.

it is shown below:

$$$