help with a polynomial

Kurre2000 · 2006-09-03 06:19:40

i need help with this problem...

find the "zeroplaces"(dont know the english name, roots?) of the polynomial
p(x)=x^2 - (a+b)x + ab
i got it to the answer (a+b)/2 +/- ((a+b)/2)^2 or something like that. but it was wrong (or maybe i can shorten it more). the answer was a and b.
how should i solve it??

and btw, is it possible to get back a lost password?

Zhylliolom · 2006-09-03 06:53:03

You can get the answer a and b by doing it this way:

Now the keen and experienced eye factors this instantly as (x - a)(x - b) = 0, which gives the answer a and b . But most people wouldn't notice this since they're used to factoring with numbers, not letters, so let's use the quadratic formula:

Then we have

and

Thus the roots(zeroplaces ) are a and b.

Zhylliolom · 2006-09-03 07:13:13

If you have forgotten your password, go here:

http://www.mathsisfun.com/forum/login.php?action=forget

Hopefully you still have the email that you registered your forum account with.

Kurre · 2006-09-03 08:14:36

thanks Zhylliolom, now i get it
and thanks for the password help, very nice

Zhylliolom · 2006-09-03 08:40:09

No problem. Congratulations on becoming a Full Member.

Math Is Fun Forum

#1 2006-09-03 06:19:40

help with a polynomial

#2 2006-09-03 06:53:03

Re: help with a polynomial

#3 2006-09-03 07:13:13

Re: help with a polynomial

#4 2006-09-03 08:14:36

Re: help with a polynomial

#5 2006-09-03 08:40:09

Re: help with a polynomial

Board footer