# my quadratic issue

Discussion in 'Homework Help' started by stupid, Nov 16, 2009.

1. ### stupid Thread Starter Active Member

Oct 18, 2009
81
0
hi,
how to simply s$^{2}$+(R/L)s + (1/LC)=0?

my work,
by quadratic
-(R/L)±√((R/L)^{2}-(4/LC)) /2 =0

-(R/2L)±√((R/L)^{2}-(4/LC)) /2 =0

-(R/2L)±(1/2)√((R/L)^{2}-(4/LC))=0

-(R/2L)±√((R/4L)^{2}-(1/LC)=0

but the answer provided is -(R/2L)±[(R/2L)^{2}-(1/LC)]^{(1/2)}

my problem is with (R/4L)^{2}

thanks

2. ### Ratch New Member

Mar 20, 2007
1,068
4
Hey Stupid,

Why do you want to keep the three elements that make up the coefficients of the quadratic equation separate? That makes for a lot of complex algebra, and does not simplify anything. Combine the elements first to make each coefficient, and then apply the quadratic formula.

Ratch

3. ### steveb Senior Member

Jul 3, 2008
2,433
469
Yes, that is your problem. Double check your work and you'll see that you just simplified incorrectly. - simple algebra mistake.