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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: lacoste on February 15, 2009, 04:42:40 pm

Title: QQ >>>> quick quadratic q
Post by: lacoste on February 15, 2009, 04:42:40 pm
ahow that the equation (k+1)x^2-2x-k=0 has a solution for all values of k.



thanks~!!!
Title: Re: QQ >>>> quick quadratic q
Post by: cobby on February 15, 2009, 04:49:31 pm
Is the equation supposed to read


or


Title: Re: QQ >>>> quick quadratic q
Post by: /0 on February 15, 2009, 04:52:31 pm
By 'a' solution I'm assuming 1 or more solutions.

The discriminant can be used to find the number of solutions. If , then the equation will have solutions.















Since , we can see that . So the equation will always have 2 solutios for any value of k.
Title: Re: QQ >>>> quick quadratic q
Post by: lacoste on February 15, 2009, 06:51:51 pm
thanks divide 0!!

cobby: the second one the x^2

Is the equation supposed to read


or



Title: Re: QQ >>>> quick quadratic q
Post by: lacoste on February 15, 2009, 07:30:15 pm
hey divide0, did you accidently place 3 instead of +3/4 at the end of the working? or did something cancel out which i dont know where?
Title: Re: QQ >>>> quick quadratic q
Post by: d0minicz on February 15, 2009, 10:24:41 pm
Before he completed the square, he took 4 out of the equation as a factor.
When hes completing the square, the 4 still remains outside as a factor.
so the cancels down to 3.
Title: Re: QQ >>>> quick quadratic q
Post by: lacoste on February 15, 2009, 10:56:02 pm
thanks dominicz.

get it now. 12/4=3 cheers