The Student Room Group
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>
Competition - post a photo you've taken of nature >>

C1 maths discriminant?

What do I do?
image.jpg234.2KB
For part A) you have to complete the square.
Part B) Use the discriminant b^2-4ac=0
Original post by moment of truth
For part A) you have to complete the square.
Part B) Use the discriminant b^2-4ac=0


You mean b2−4ac<0b^2 - 4ac < 0. Your version gives repeated real roots.
Reply 3
Avatar for jadechapell
jadechapell
OP
Original post by moment of truth
For part A) you have to complete the square.
Part B) Use the discriminant b^2-4ac=0


How do you complete the square? Is it like (x+b/2)^2 -b/2 then something?
Original post by jadechapell
How do you complete the square? Is it like (x+b/2)^2 -b/2 then something?


I've drawn out a graphical example of completing the square. It may make it easier to remember if you can visualise what you're actually doing:.

comp-square.jpg

Maybe it should really be called "completing the difference of two squares" though, as that's the kind of expression you end up with.
Original post by atsruser
I've drawn out a graphical example of completing the square. It may make it easier to remember if you can visualise what you're actually doing:.


That is really interesting - it bears no resemblance to the method/explanation that I use - it is always interesting to see a new slant on a topic
Original post by TenOfThem
That is really interesting - it bears no resemblance to the method/explanation that I use - it is always interesting to see a new slant on a topic


How do you explain it?
Original post by atsruser
How do you explain it?


By completing the square

We know what (x+a)^2 is

And then we add the extra bit to make it the same as the function required

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you