Solving Quadratics by Using the Quadratic Formula

You remember this one, don't you? Opposite of b, plus or minus... what was it? Well instead of just telling you, why don't we derive the formula? As it turns out, it's like completing the square, but with variables. Will you just watch this already? I can't explain it without the pictures.

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[Tom-xbml]

Having seen a few videos from khan academy, worked with various math websites, even tried a book algebra 1 for dummies, this is MILES ahead of everything else. The way you get to the point and pack everything densely, yet still manage to explain everything fully is amazing. This entire polynomials only took me a good hour to master. Thanks!

[madmanstewy]

What a god of maths, watching these videos and it's changing how I see maths

[yeeiii]

As a G11 STEM student studying math for my college entrance exam, I thank you Math Jesus from the very bottom of my heart for this playlist. This makes math so easy to understand. Love from the Philippines 🇵🇭 🫶🏻

[gracebumpus]

Thank you for this! I seriously never learned to derive the quadratic formula in HS. I always just did it. But now I LOVE knowing the whys of math. Thank you!!

[Chuckom]

I think an important point that should be emphasized in explaining the derivation of the quadratic formula is making sure people don't confuse coefficients with variables; they shouldn't treat the coefficients a, b, and c in the same manner they treat the variable x. It is so easy to see a letter in algebra and automatically treat it as a variable even in situations where the letter stands as a coefficient for a constant. This was a big stumbling block for me when I was first taught how to derive this formula. I suspect many people who learn this will have a similar struggle.

[nehasingh]

The real taste of mathematics comes over here when you not just lethal yourself from the formulas else by learning the real concepts.
Thanks Sir Dave

[filiomusic]

Wow, honestly a crazy good series! Poignant explanations, no getting caught up in unnecessarily complicated academic terminology, structured perfectly logically from episode to episode. Makes all of this seem super easy - which it is with the right teacher! Really helping me brush up on my fundamentals. Thanks so much!

[ceegae]

I've never been this pissed bro my teacher briefed through this formula like a side hustle when infact I could've solved polynomials in 3 secs with this....literally dropped it last 15 secs of class and told us to remember w/o telling anyone it's purpose

[thegoodlydragon]

Thanks, Dave! In school I remember all they told us was the formula itself and that if we plug in the numbers and do the arithmetic right we'll get the answer. But until seeing this video I had never actually seen an explanation of what the formula actually is or the logic behind it! Teaching the actual subject, what a novel idea!

[idlehands]

I can still remember the quadratic equation 35 years after learning it. This video is a good refresher on what it actually means as 10 minutes ago I didn't have a clue.

[zerosandones]

On the 2nd question here in 6:10 why are both the answers positive?

-13 + 11 over 6 is -1 over 3 (simplest form)

-13 -11 over 6 is -4 since the answer is -24 over 6

Can someone explain pls

[NickHope]

COMPREHENSION #3 SOLUTION
Quadratic Polynomial form: ax^2 + bx - c = 0
Quadratic Formula: x = (-b ± √(b^2 - 4*a*c)) / (2*a) - Lots of extra brackets to make precedence clear because I'm only writing on one line.
8x^2 + 14x - 15 = 0
∴ x = (-14 ± √(14^2 - 4*8*(-15)) / (2*8)
∴ x = (-14 ± √(196 - (-480)) / 16
∴ x = (-14 ± √(196 + 480)) / 16
∴ x = (-14 ± √676) / 16
∴ x = (-14 ± 26) / 16
∴ x = 12/16 or -40/16
∴ x = 3/4 or -5/2

[kangmyungjae]

First time feeling math is beautiful... at 22... starting physics major... wish me luck

[monke]

Thanks Professor! You're such a great person to give such beautiful FREE lessons on YouTube! Unbelievable.

[yourresttime]

it just blew my mind - in a good sense ❤

[PalasBrown]

incredible! wow, very good teaching method. thank you professor dave!

[VikashKumar-uqpy]

In India, this formula is known as shri dharacharaya rule

[Carrymejane]

Woah it takes me 3 days to comeback here again after learning total about polynomials

[ohmygodestovaaserepicopapu]

2:32 question, where did the 4a/4a come from?

[Certifiedkangkongchips]

how did you combine it in 4:31 pls help