+0  
 
+5
282
1
avatar+266 

 

???

 Mar 17, 2016
 #1
avatar+96262 
0

1)   -1x^2  - x = 3 = 0

 

Possible rational roots  = all the possible factors of -3 over all the possible factors of -1   = ±1, ± 3

 

 

2)    2x^3  + 2x^2 - 19x  + 20  = 0

 

Well...by cheating...[looking at the answers]....I can see that one root is -4

 

So....using some synthetic division....we can find the remaining polynomial

 

-4  [  2   2     - 19     20 ]

            -8        24    -20

       ------------------------

       2   -6       5         0

 

So....the remaining polynomial  is    2x^2   - 6x + 5

 

And using the quadratic formula,  the other two roots are 

 

x =   (  6 ±  √[ 36 - 40] )  / [2(2)] =    [ 3 ± i ] / 2

 

 

 

cool cool cool

 Mar 17, 2016

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