IGCSE/GCSE/O & A Level/IB/University Student Forum

Qualification => Subject Doubts => GCE AS & A2 Level => Math => Topic started by: cooldude on March 18, 2010, 02:55:00 pm

Title: p1 cie question
Post by: cooldude on March 18, 2010, 02:55:00 pm

why is root x always postive, for example why do we consider root 4=2 and not +/-2.

Title: Re: p1 cie question
Post by: astarmathsandphysics on March 18, 2010, 03:31:54 pm

There are 2 roots. Why do you ask this

Title: Re: p1 cie question
Post by: cooldude on March 18, 2010, 04:51:20 pm

Quote from: astarmathsandphysics on March 18, 2010, 03:31:54 pm

There are 2 roots. Why do you ask this

because our book says this, for example when x^0.5-6-x
we get x=4,9
they say root x=3,2
and since 6-9=-3 they say that 9 does not satisfy the original equation as they are not considering root x=-3, as they say that root x=>0, so i am asking why is root x=>0?

Title: Re: p1 cie question
Post by: astarmathsandphysics on March 18, 2010, 07:07:53 pm

Only because the question says or because x is b length for example:)