99% of Algebra Students Make Mistakes With This! Will You???

How to solve a quadratic equation by using the quadratic formula.
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[@royalredbird9717]

I'm in 10th grade, and this is the main reason why I started using parentheses,(enclosing everything in parentheses) instead of the regular multiplication sign. To remove ambiguity.

[@patriciagreen2365]

Excellent problem solving skill!!

[@robertakerman3570]

I believe this was an excellent adventure

[@tomtke7351]

Using parentheses will be very welcomed when writing computer programs.... I can't live without them as they simplify "order of operations."

[@vietran0425]

To make this issue less confusing: Please move -2x to the right: -2x = 7x(2) + 1 7x(2) + 2x + 1 = 0 a=7, b=2, c= 1

[@DarVV]

75% of people above 18+ years old and option. 26+ y.o. after the last exams in their live) can, simply saying, forget about "bb-4ac". Exceptions are: the active teachers, reserchers, enginers and the people using math as a hobby many years after finishing their school-days.

[@jlwoot]

Is it wrong to move the -2x to the other side and have 7x^2 + 2x +1 = 0 ? Also, I believe it is proper form to not have negatives in the denominator for the final answer.

[@mr.mxyzptlks8391]

I think this one plays with signs on purpose😅 I would have factored out -1, divide by it (allowed right?) and end up with all positives. Or, instinctively move -2x to the right. And,moving from R to C, mention that this is the principal solution. There are more solutions to be found 🎉

[@pgskills]

That's exactly my question. If you initially change it to 7x(2) + 2x + 1 you end up with a negative sign on the 1 up top rather than the 7 down below in the final solution, right? Are those equivalent?

[@WmLatin]

I wondered the same. This deserves an answer.

[@mohamedkazema6381]

@@pgskills Yes, it is the same answer.

[@pgskills]

@@mohamedkazema6381 Thanks. I wasn't sure and it was really bugging me.

[@antoniorodriguezsolis53]

I got negative 1 + i square root of 6 all over 7.

[@leetrask6042]

The square root of a negative number I can't imagine the answer.

[@busby777]

this makes no sense to me. I was taught that the proper form of a quadratic equation was (X + Y) (X + Y) = X SQUARED PLUS 2XY PLUS Y SQUARED.

[@pgskills]

Yes. The quadratic formula shown here is what you need to use when you can't simplify such an equation down to a simple (X + Y) (X + Y). You can test it out with one of those simpler quadratic equations to see that it works. Try it with 2X(squared) + 3X + 1 and you'll see you get the same two answers as factoring it down to (X + Y) (X + Y). Nowadays they don't usually even teach the quadratic formula until you're in an advanced algebra class, probably in high school. It used to be taught in most 8th grade algebra classes though.

[@tobyharnish8952]

I think he should just give up his channel and let me take it over. This guy teaches some very basic and elementary mathematics. I mean, how hard is to do this? I believe a first grader can get this right. By the way, I consider my self as a first grader. I just wonder if I can solve this. If I can, I think that proves my point. Okay, let me begin. The problem is -2x = 7x^2+1 Well, the first step is always to write this equation in standard form: 7x^2+2x+1=0 Now, using the quadratic formula, we can substitute the appropriate values and solve this equation. (-2)+-\sqrt[(2)^2-4*7*1]/2*7 The next step is to simplify inside the square root symbol. x=(-2)+-\sqrt[-24]/2*7 Next, simplify the denominator x=(-2)+-\sqrt[-24]/14 Okay, here comes the tricky part. We cannot take the square root of -24. So, just write it as the square root of 24 times i (i is the square root of -1). After this, we would get x=(-2)+-\sqrt[24]i/14 Notice that we can simplify this even more. We can write 24 as 2 times the square root of 6. x=(-2)+-2\sqrt[6]i/14 We are not done yet. We can cancel out a 2. x=-1+-1\sqrt[6]i/7

[@pgskills]

Teaching is actually not nearly as easy as it looks. You've fallen prey to our societal bias that actually espouses the moronic "Those who can't do, teach" canard. They're separate skills and it's rare to find someone who can really do both well. This guy seems like an excellent and very encouraging math teacher and I'm sure his students benefit from his instruction.

[@tobyharnish8952]

@@pgskills Hi PG Skill, I apreciate your comment and correction. If I am not mistaken about your remark, you seem to support a teaching system that is used in today's school. If you do not mind, I shall make a few points of my own. 1. A teacher must know well the subject that they are teaching. If a teacher fails in this area, they simply cannot teach. 2. Please note that teaching and knowing the subject are both important (you have stated one is more important than other). 3. He has done multiple videos on the quadratic formula. It seems like he is making videos that does not help anyone. If you look his KZbin channel, most of his videos are the same (or at least similar). 4. He claims that he will upload Calculus videos on this channel. However, there is not much of it (most of them were basic calculus concept). I hope you understand my kindness and goodbye

[@pgskills]

@@tobyharnish8952 "you seem to support a teaching system that is used in today's school" What part of my comment says this? "you have stated one is more important than other". Again...where? Good luck with your teaching career.

[@greenmanofkent]

What's your point here? You have followed the same steps (with the sole exception that you didn't have the minus signs, he did) that the OP did, and not surprisingly, arrived at the same answer. Remember he is aiming this video at those who are not familiar with the quadratic formula. For those of us who do know what it is and how to use it, it seems trivial, but we struggled with it once as well.

[@harrymatabal8448]

Mr Toby I just love your comment. I am positive that you will do a better job ok