Register to reply

Polynomial Functions

by josephcollins
Tags: functions, polynomial
Share this thread:
Jun19-04, 05:47 PM
P: 60
Could someone please help me with this question, I'd be most obliged:

Q) Find the value of "a" for which the function
2x^3 - ax^2 - 12x - 7
has a repeated factor.

Phys.Org News Partner Mathematics news on
Professor quantifies how 'one thing leads to another'
Team announces construction of a formal computer-verified proof of the Kepler conjecture
Iranian is first woman to win 'Nobel Prize of maths' (Update)
Jun19-04, 06:40 PM
Sci Advisor
PF Gold
Gokul43201's Avatar
P: 11,155
If you mean two identical roots, then ...

write [tex] 2x^3 - ax^2 - 12x - 7 = (x-b)^2(2x-c) [/tex]

Expand the RHS and compare coefficients. You have 3 equations in 3 unknowns.
robert Ihnot
Jul4-04, 12:59 AM
PF Gold
P: 1,059
Since we are seeking only a specific solution, we can keep in mind that if the cubic has a double root, that this root is also present in its derative. The derative is: 2(3X^2-aX-6). Here if we let a =3, we get X =2, -1. -1 works in the original equation and the factoring then is 2(x+l)^2(x-7/2).

Register to reply

Related Discussions
Max/Min of Polynomial Functions Calculus & Beyond Homework 4
Polynomial Functions w/ zeros. Precalculus Mathematics Homework 1
Polynomial Functions help Precalculus Mathematics Homework 3
Polynomial evaluation functions Calculus & Beyond Homework 4
Root of polynomial functions General Math 1