Question

F. determine if (x + 3) is a factor of (x) = 2x3 + x2 –8x + 21 by using synthetic division. if so, find the other factors.

Answer 1

Since its x + 3 we use -3


-3| 2      1      -8      21           (these are the # without the x)
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            -6     15     -21      
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    2      -5      7        0               
 
Drag the 2 down, multiple it by -3 to get -6 
1+(-6) = -5. -5 * -3 =15 . 15+(-8) = 7
7*-3 = -21. -21 +21 = 0 
Since last # is 0 we have a factor.


 factor is 2x^2 -5x -7 (we start with a power 1 less the original.)

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