Using the Discriminant in a Quadratic Equation

The Discriminant is a useful tool to understand the nature of the roots (how many, what type) of a quadratic equation.

Category:

Howto & Style

Tags:

• discriminant
• solve
• solving
• quadratic
• equation
• math
• mathematics

[DarkWolfen]

No answer for a negative square root? What about i? A complex number?

[minkusbc]

Of course imaginary and complex numbers can be used. But at the high school level, these are usually not discussed until calculus. However, as curriculums change, I may redo this and add it in. Thanks for your interest.

[shoes202]

you never discussed the discrimant how to find it! Why use it in ur title if ur not even gonna talk bout it?

[minkusbc]

I show in the first step - it is the b^2 -4ac part of the quadratic formula. A quick look at the value of the descriminant will tell you how many answers your equation will have.

[Supersmashbrojory]

Or better yet, just look at the degree of the function. If you are using the quadratic formula, you are dealing with a quadratic function and a quadratic function has two x values in which f(x)=0. The degree of your function is how many zeroes the function has, the degree being largest exponent.

example: f(x)=x squared+x+1. the highest degree is two therefore, you will have two zeroes.

[minkusbc]

You still need the discriminant to tell you how many of those zeroes are real numbers and how many are imaginary numbers. Most Secondary math curriculums do not discuss imaginary numbers until calculus or advanced placement.

[MrAstroKind]

This is great, I understood how to do this before this video but it's good revision!

[XopenwideX]

I use this to finish my homework and to finally understand it! (my teacher sucks)

[MrPimpdaddy8]

5/5 you made it easier on my head!

[MrPimpdaddy8]

@minkusbc hey im in algebra 2(11th grade) and i have learned that i is a imaginary number bcuz the square root ends up negative...is that right?? thats what yall talking about?? is my teacher correct or shes stupid like i??

[bobmarley789456]

Great video this was really helpful

[dardi1111]

im 16 we use imaginary numbers could u pls answer this in a video

Re(z(2+1))=1 IM(1/2+i)=-3/5

[devpwner]

For example two, you could answer it by taking the negative off of -71 and put I infrount of the square root indicating you have imaginary numbers. from there you would simplify the number in the square root which would be +71 if possible.

[XxAngelShinn]

dude i agree with you 100% but my dad makes me go =/

[yeegf]

kumon is hopeless.

use youtube.

tell everyone you know in kumon.

[XxAngelShinn]

omg you helped me so much thanks!! im in kumon and this self studying/learning isn't working for me anymore and after you explaned it to me i really got why and how to use it, thanks so much!