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Can someone please explain this?

 

(x-2)f(x)=x^3 - 4x^2 - 11x + 30

 

By comparison we take

f(x)=x^2 + bx + c

(x - 2)(x^2 + bx + c) = x^3 - 4x^2 -11x + 30

 

Therefore

 

bx^2 - 2x^2 = -4x^2

x^2(b - 2) = -4x^2

 

Thanks!

 Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016
edited by Guest  Jul 6, 2016

Best Answer 

 #1
avatar+37103 
+5

Divide both sides by (x-2)

to get

f(x) = x^2-2x-15    or  f(x) = (x-5)(x+3)

 Jul 6, 2016
 #1
avatar+37103 
+5
Best Answer

Divide both sides by (x-2)

to get

f(x) = x^2-2x-15    or  f(x) = (x-5)(x+3)

ElectricPavlov Jul 6, 2016
 #2
avatar+129842 
0

(x-2)f(x)=x^3 - 4x^2 - 11x + 30

 

I believe that we want to find "f(x)"    ......we can do this using polynomial long division

 

 

             x^2   - 2x      -15 

x - 2  [   x^3   - 4x^2   - 11x   + 30  ]

             x^3   - 2x^2

             ----------------------------------

                     -2x^2   -   11x

                     -2x^2   +     4x

                    ---------------------

                                    -15x    + 30  

                                    -15x   +  30

                                 -----------------

                                                 0

 

So....f(x)   =  x^2 - 2x  - 15

 

And notice that this can be factored as ( x -5) (x + 3)

 

So

 

x^3 - 4x^2 - 11x + 30  = (x -2) f(x)   =  (x -2) ( x^2 - 2x - 15)   =  (x -2) (x -5) (x + 3)

 

 

 

cool cool cool

 Jul 6, 2016

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