09 - The Quadratic Formula Explained, Part 1 (Practice Problems & Solutions)

View more lessons at www.MathAndScience.com.
In this lesson, you will learn what the quadratic formula is, how to use it, and why it is important to solve quadratic equations in algebra.
First, we will derive the quadratic formula using the completing the square method. Next, we will solve numerous quadratic equations using the quadratic formula and check the answers.

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[@akramshaheen2481]

Bro your 35 and studying quadratic formula I'm 14

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[@YourWrongImRight933]

@@akramshaheen2481 bro you’re 14 studying quadratic formula im in 7th grade

[@jonnukisan9759]

Now I'm glad that I learned completing the square before learning the quadratic formula! You made it so clear how they are derived. Thank you, great punch line

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[@majorynambeye3943]

You are best. You really explain the work very well. Thanks for making me understand how the quadratic formula is derived.

[@user-pp6gp6zb2k]

I always enjoy this style

[@zhengzhang3903]

One thing I would like to mention is that 15:33 if a is negative, and you take the square root of 4a^2 you can get -2a. But since there is a plus or minus sign in the front, it does not change the form.

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[@MathAndScience]

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[@smendetv1105]

A blow by blow account of the derivation...much better clear as daylight

[@MathAndScience]

Awesome!

[@Shoreline4Iron]

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[@user-xw3do9lp9x]

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12:12 is reassuring. That even the best of the best would be losing sight of the tail end of this thing they are unravelling if they look aside even for a brief moment

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Can you prove the quadratic formula? Jason, here is an idea for you. Why not make videos in terms of math proofs? I am sure that math majors would love you for it.

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Thank you!

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Thanks

[@rubiegamble898]

I'm trying to get my GED and I need to learn the Quadrtic Formula.

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THANK YOU... SIR...!!!

[@sandrarr5434]

Hello there I'm studying the AQA foundation and I wondered if you could tell me how does one know when to apply the Elimination process t o simultaneous equation and when to apply substitution what is the distinctive different that I should know please.? Is it when there's an X Square coefficient

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[@haykghukasyan6555]

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[@user-yn3ev1oy1j]

At 7:58 why do you have to divided by 2 and square root answer please I need really help please I hope you reply.

[@carolinemarie44]

Please tell me about the i. I'm jus learning all this.

[@user-yn3ev1oy1j]

At 7:58 why do you have to divided by 2 and square root it pleases response I hope you see it

[@Yesmayo1982]

why is b/ax divided by 2 then squared? WHy not do the same with x squared and -c/a?

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[@ritam20071]

This method is called Sridharacharaya method discovered in 10th century AD by Indian mathemetician

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[@johnmaulkin-ur8lm]

Fantastic job but i am confused; at 13.19 mins. b/2a.x + b/2a.x = b/a.2x. Please help. Thank you.

[@worknehgebeyehu9598]

Thank you teacher

[@MathAndScience]

You are welcome

[@theophonchana5025]

b^(2) - 4ac = 13

[@theophonchana5025]

b^(2) - 4ac = -36

[@jonnukisan9759]

an endless accordion of whiteboards! awesome

[@theophonchana5025]

b^(2) - 4ac = 20

[@apoll0626]

why do you prime factorise

[@vaibhavsingh8361]

Quadratic Formula is Known as Sri Dharacharya Fomula Which is Derived from Indian Mathematician

[@ChavoMysterio]

Here's a fun fact about me: I first learned about the quadratic formula in Geometry.

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@Jason Gibson

[@MathAndScience]

Thank you so very much! I really appreciate the kind words!

[@Koreanbosuji]

@@MathAndScience :-D Anytime - welcome

[@sawdustwoodchips]

Completing the square allows you to find the turning point of the quadratic.

[@stevenscottoddballz]

3:52 I keep hearing "Always get 2 solutions", but when I did [3A² = 6A - 3], there was only ONE solution.

[@jozef-aerts-wiskunde]

You have 2 , 1 or 0 solutions , depending on the value of d^2 -4ac ( called discriminant )

[@stevenscottoddballz]

@@jozef-aerts-wiskunde I am VERY familiar with the discriminant. I have had trouble with [S² + 7/4 = 1/2]. I don't know what to do with the 2 in the discriminant.

[@Ihuoma307]

Waw nice

[@theophonchana5025]

#QuadraticEquation

[@ownagebox]

at my time we only learnd the pq-formula

[@solomonigba2580]

I have some questions here

[@TheByzmal]

(Ques) I 15 min & 35 secs. Why did you square root the denominator & not the numerator.? You only square root 4ac^2 & not the terms above it. Why?

[@MathAndScience]

I did take the square root of the bottom. The answer was 2a.

[@TheByzmal]

@@MathAndScience I see & know that, I am asking about the top. Why didn't b^2 - 4ac became b - 2ac?

[@clairgarrick9842]

I always forget how to derive the quadratic formula from completing the square.

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[@kainacorsiga3590]

Oh

[@Tarzanaxx]

Square root of. 20 IS NOT 5. ERROR IN EXAMPLE.

[@Tarzanaxx]

Square toot of 20 is 4.47…

[@theophonchana5025]

a = 3 b = 1 c = -1

[@theophonchana5025]

y^(2) - 4y + 13 = 0 y = (- (-4) + sqrt (-36) ÷ 2 y = (4 + sqrt (-36)) ÷ 2 y = error

[@khalilfuller4939]

So it will be +/- 6i

[@khalilfuller4939]

So it will be +/- 6i

[@zbigniewbrzezinski8869]

You forgot -1 on the equation ! (First example)

[@theophonchana5025]

sqrt (-36) = error

[@khalilfuller4939]

i root

[@theophonchana5025]

sqrt (-36) = invalid input

[@MathAndScience]

You need to get a calculator that can give you a result that is an imaginary number. When you take the square root of a negative number a regular calculator cannot compute the answer but a scientific calculator will give you an imaginary answer which is the correct answer.

[@theophonchana5025]

a = 1 b = 6 c = 4

[@user-ic3dn3vu9u]

this formula is called shree dharacharya formula

[@nickmasters6239]

stop looking at the comments and look a the video

[@jessethompson8606]

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[@nripeshkumarmishravinayak664]

SRIDHARACHARYA RULE

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[@user-yc6rd5pq9e]

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