Quadratic Function: Positive definite (1 Viewer)

[Makro]

For which values of m is the quadratic function y=mx²-2x+m positive definite.

I know Discriminant has to be < 0, and a > 0. But can someone explain what to do exactly? The answer confuses me.

 

[lyounamu]

For which values of m is the quadratic function y=mx²-2x+m positive definite.

I know Discriminant has to be < 0, and a > 0. But can someone explain what to do exactly? The answer confuses me.

If it is positive definite, it's discriminant must be less than 0.

First, find the discriminant of the function.

i.e. discriminat = (-2)^2 - 4 x m x m = 4 - 4m^2
so 4-4m^2 <0

m^2 - 1 > 0
(m+1)(m-1) >0
so m >1 or m<-1
but since m > 0 because the graph is positive,

m > 1 is the answer

 

[Timothy.Siu]

For which values of m is the quadratic function y=mx²-2x+m positive definite.

I know Discriminant has to be < 0, and a > 0. But can someone explain what to do exactly? The answer confuses me.

discrimant = 4-4m^2
discriminant <0
4-4m^2<0
(2-2m)(2+2m)<0
m>1 or m<-1
but it has to be positive definite...so it has to concave up, so m has to be >0 so m>1,
i dont know why i did it, since it was already done

 

[lyounamu]

discrimant = 4-4m^2
discriminant <0
4-4m^2<0
(2-2m)(2+2m)<0
m>1 or m<-1
but it has to be positive definite...so it has to concave up, so m has to be >0 so m>1,
i dont know why i did it, since it was already done

You cannot overcome your love for maths. That's as simple as that.

 

[Makro]

Thanks for that.

 

[jan170891]

Is maths suppose to be that interesting for u guys?

 

[lyounamu]

Is maths suppose to be that interesting for u guys?

Hahaha.. not necessarily

We just do it to help others. My earlier was a joke.

Maths can be fun sometimes. It's like you enjoying playing sport, game or other stuff. Same theory applies.