Example 2: Using the quadratic formula | Quadratic equations | Algebra I | Khan Academy

Quadratic Formula 2

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[susantparida]

5:12 you forgot to divide by two. its 4-√15 or 4+√15.
Hope you understand.

[Surannhealz]

Breaking down the square was very helpfull info. Thanks again!

[ebenezermudosa]

it really helped me with my homework i subscribed.

[marieschrag]

**changes playback speed from 1 to 1.25 and changes all history as we know it**

[mehdisajjadi]

there must be some mistake . i think the answers are 4-rad(15) and 4+rad(15)

[salesmgrproduce]

I thought the formula for when "b" is an even number, it's "x= -b' squared plus or minus the square root of b' squared minus ac over a"?? so wouldn't the formula be "ax squared + 2b'x +c= 0 when a doesn't equal 0"

[Daski]

could someone please explain why let's say

-8 + 2 all over -2 is 4-1 and not 4 + 2... wouldn't the -2 as the denominator cancel out with the -8 and become 4? why is it not so?

[salesmgrproduce]

wouldn't that be the quadratic formula II? 8 is an even number, so i thought you use the quad. formula 2 for when the coefficient of x is an even number, and use the quadratic formula 1 when the coefficient of x is an odd number.

[OuttaEgypt]

You make this look like shooting fish in the barrel xD

[twentysecondcenturywoman]

64 - 4 (1) = 64 - (-4) ?? Isn’t that it??

[nox]

i still don't understand this. Why don't you break it down more?