No real roots question (1 Viewer)

[BlueGas]

For what values of k does x^2 - kx + 4 = 0 have no real roots? I know how to find k but I don't know how to write my final answer, the final answer for this question is - 4 < K < 4, but how do I know to write it like this?

 

[Squar3root]

delta < b^2 - 4ac for no real roots

 

[davidgoes4wce]

my working and explanation

 

[kawaiipotato]

delta < b^2 - 4ac for no real roots

For OP, this is because in the quadratic formula:

 

[Squar3root]

For OP, this is because in the quadratic formula:



$ If the the thing under the Squar3root $ (b^2 - 4ac) $ is less than zero, then it gives unreal roots since you cannot square root negatives in the real field. $

ayyyy

 

[BlueGas]

Guys I know how to find the values for K but how do I know to write it like this? - 4 < K < 4

 

[Squar3root]

Guys I know how to find the values for K but how do I know to write it like this? - 4 < K < 4

davidgoes4wce said is the solution for no real roots so graph the parabola and look at where the inequality satisifies which is when

 

[calamebe]

Guys I know how to find the values for K but how do I know to write it like this? - 4 < K < 4

Yeah, you would write: this equation has no real roots for -4 < k < 4.

 

[Flop21]

Guys I know how to find the values for K but how do I know to write it like this? - 4 < K < 4

-4 is less than x, which is less than 4. That's how you 'say' it. So by graphing it you can see, the x values are between -4 and 4, hence -4 < x < 4