[katesimpson2112]

Hi,
I am a GCSE maths student, and I need some help with a parabola minimum point question I was doing for revision.
When a question asks 'find the minimum point' and gives you the equation of the parabola, what do you do after you complete the square?

For example, the question used the equation x squared - 8x +23

I then wrote this out as (x-4) squared + 7

Does this mean that y=7 and x=-4 ? Or do I put it into the first equation?

[james.h]

(Original post by katesimpson2112)
Hi,
I am a GCSE maths student, and I need some help with a parabola minimum point question I was doing for revision.
When a question asks 'find the minimum point' and gives you the equation of the parabola, what do you do after you complete the square?

For example, the question used the equation x squared - 8x +23

I then wrote this out as (x-4) squared + 7

Does this mean that y=7 and x=-4 ? Or do I put it into the first equation?

Almost, check the sign on your x-value.

The smallest value (x-4)² can take is zero, since squared numbers are always positive. So you can immediately see that the minimum point, y=7, will be where the squared bracket is zero, i.e: where x-4=0.

[katesimpson2112]

So do you mean that:
If x-4=0, then x=4 ? And y=7?
Sorry, I just get a tad frustrated due to my slightly incompetant teacher who didn't finish teaching us the syllabus :L

[Brand New Eyes]

(Original post by katesimpson2112)
So do you mean that:
If x-4=0, then x=4 ? And y=7?
Sorry, I just get a tad frustrated due to my slightly incompetant teacher who didn't finish teaching us the syllabus :L

Yes.

(Original post by katesimpson2112)
Hi,

Does this mean that y=7 and x=-4 ? Or do I put it into the first equation?

They're both the same equation just written differently so will produce the same result.

[katesimpson2112]

Thanks, both of you!