How do you long divide (2n^3 + 0n^2 - 14n + 12) /(n + 3)2n3+0n214n+12n+3?

1 Answer
Aug 7, 2015

2(n-2)(n-1)2(n2)(n1)

Explanation:

Assume n+3n+3 is a factor for the numerator and infer the other factor:
2n^3-14n+12=(n+3)(an^2+bn+c)=2n314n+12=(n+3)(an2+bn+c)=
an^3+(b+3a)n^2+(c+3b)n+3can3+(b+3a)n2+(c+3b)n+3c

This gives the result:
a=2a=2
b+3a=b+6=0=>b=-6b+3a=b+6=0b=6
c+3b=c-18=-14=>c=4c+3b=c18=14c=4
3c=123c=12

Therefore n+3n+3 is a factor and we have:
(2n^3-14n+12)/(n+3)=(cancel((n+3))(2n^2-6n+4))/cancel(n+3)=
2(n^2-3n+2)=2(n-2)(n-1)