Can someone help me with this pre-Calculus question?

Oct 2012
3
0
Chicago
If 2x2-dx+(31-d2)x+5 has a factor of x - d, what is the value of d if d is an integer? (Crying)
 
Dec 2011
2,314
916
St. Augustine, FL.
Let:

\(\displaystyle f(x)=2x^2-dx+(31-d^2)x+5\)

If \(\displaystyle f(x)\) has a factor of \(\displaystyle x-d\) then \(\displaystyle f(d)=0\).

Hint: use the rational roots theorem on the resulting cubic in \(\displaystyle d\).
 

skeeter

MHF Helper
Jun 2008
16,217
6,765
North Texas
post problems in the precalculus forum please.
 
Oct 2012
3
0
Chicago
so if f(d)=0 then then the new f(x) is 2x^2+31x+5??
 
Dec 2011
2,314
916
St. Augustine, FL.
No, that doesn't mean to let d = 0, that means when x = d, f(x) = 0.