Quadratic Inequality (part 2) : ExamSolutions

[clairbearushin2dstar]

Hi I like your videos but in class we learnt how to do then without a graph and I was wondering if you could upload a video on how to do it without the graph. Thanks

[ExamSolutions]

@clairbearushin2dstar There are several ways that you can do this without a graph. In my opinion as a teacher, I would encourage you to learn the graphical way as it develops in the long term better understanding of the concept, it is very quick and has further implications if you continue with further maths where graphical methods of solving inequalities are used.

[LUTENUKEM]

isn't it going to be a downwards parabola

since in the first equation has a negative on the x(squared)?

hmmmm....

[ExamSolutions]

I multiplied by a negative value so the x squared term was positive in order to draw a u shaped parabola. The inequality sign must be reversed though.

[Penndennis]

First of all - I just love your vids., thank you very much. If you have time to reply, I'd be much obliged.

I factored out -1 from the original equ. (if that's the correct way to say it)

(-1)(x^2+x-6)>0

(-1)(x+3)(x-2)>0

This led to-:

(-x-3)(x-2)>0

When multiplied it gives your original equ. -x^2-x+6>0

This gives an upside down U and so I think I'm right in not switching the inequality sign? or have I misunderstood what's going on?

[ExamSolutions]

That is fine. You get the same result by now considering the part of the curve above the x-axis. ie -3<x<2

[kdatcs]

how are you doing the effect with the pen writing on the paper? i like to make videos too and i have never seen anything like this

[dj222444]

This dude's voice made me want to go to sleep. sort of hypnotic in a way...

Very useful though

[prashad]

Great... Helped me understand this topic with ease.

Cheers

[sumit270]

you saved me from making that stupid mistake that i always make

[eatmoremonsters]

YOur voice is hypnotic, this vid was very useful. Thankyou alot.

[canadaonly2]

another great vid, well done

[Wacko375]

When would you draw a negative parabola??? Please reply quick. My exam is in 5 days.

[gerardocoria]

you draw an upside down parabola when the a value for the quadratic equation is a negative number for example y= -2x+3x+2. the negative 2 is the one that determines which way the parabola opens.

[womatama]

opps i remember this formular u dnt hav 2 draw a graph

[womatama]

do we HAVE 2 do a graph?

[Runekilla]

u dont have to but it makes it much easier

[betaiv]

wouldn't be easier to use the quadratic formula?

[KenY2Ken]

Why can't it be a sketch? It's just so you can see which side of the critical values y is below 0.

Great tutorial, keep them going.

[mkchelsea]

I have always had a problem with this, this helped alot! Thanx!

[thedirtygermans]

that tutorial sucks!

the line (parabola) should be drawn correct! not to sketch!

[Runekilla]

rofl no it doesnt, he only needs to find the the X value