Watch Video on The Quadratic Formula - Algebra Help
Access full lesson containing this video at: http://www.yourteacher.com/algebra2/thequadraticformula.php Students learn to solve quadratic equations in the form ax^2 + bx + c = 0 using the quadratic formula, which states that x = -b plus or minus the square root of b^2 — 4ac over 2a. For example, to solve the equation x^2 — 3x — 8 = 0, since a = 1, b = -3, and c = -8, the quadratic formula states that x = 3 plus or minus the square root of (-3)^2 — 4(1)(-8) over 2(1). Simplifying on the right side of the equation, x = 3 plus or minus the square root of 9 + 32 over 2, or x = 3 plus or minus the square root of 41 over 2, which is the final answer. Note that students also learn to derive the quadratic formula using completing the square in the first example problem in this lesson.
Duration : 0:3:39
[youtube s80J2dAUUyI]
August 26th, 2009 at 9:07 pm
you know what i can …
you know what i can do math check this out solve this problem people
August 26th, 2009 at 9:07 pm
wtffff?@?!?!?!
wtffff?@?!?!?!
August 26th, 2009 at 9:07 pm
no they cary over …
no they cary over as negatives a problem like this is just (as my teacher would say) plug and chug
plug in what it askes then solve hardest part is remembering the stupid equation
August 26th, 2009 at 9:07 pm
look in the square …
look in the square root it was (-4)(1)(-4)
-4×1 is -4
-4x-4 is a positive 16
August 26th, 2009 at 9:07 pm
3:34 epic finisher, …
3:34 epic finisher, i gonna do the square-up to all my maths answer from now on
August 26th, 2009 at 9:07 pm
he got 16 by …
he got 16 by multiplying -4×1x-4 try it on your calculator
August 26th, 2009 at 9:07 pm
Bravo
Bravo
August 26th, 2009 at 9:07 pm
I think that the …
I think that the pq-formula is much better to use when the [x^2] term is alone.
pq = -p/2 +-*SQUARE(-p/2)^2 - q
pq = x^2+px+q = 0
August 26th, 2009 at 9:07 pm
That is right.
…
That is right.
The problem with using the quadratic formula is that students forget that two minuses equal a plus, as does minus times minus.
August 26th, 2009 at 9:07 pm
9-4(1)(-4)
9{-4(1) …
9-4(1)(-4)
9{-4(1)(-4)} so negative 4 times 1 is -4. -4 times -4 is positive 16 [THIS IS HOW HE GOT 16]
August 26th, 2009 at 9:07 pm
i got this except …
i got this except for how he got the number 16…. hmmm
help me out someone?
August 26th, 2009 at 9:07 pm
i think he did it …
i think he did it wrong. he should have made the 3 and 4 (b and c) positive because there are two negatives.
August 26th, 2009 at 9:07 pm
THANKK YOU SO MUCH! …
THANKK YOU SO MUCH!
helped alot!
August 26th, 2009 at 9:07 pm
this was highly …
this was highly informative and i think all teacher should use this instead of making us remember the complicated way.
August 26th, 2009 at 9:07 pm
Hi person reading …
Hi person reading my comment
how did u get here?
August 26th, 2009 at 9:07 pm
OMG, me too! I’m …
OMG, me too! I’m tkaing mine this Monday. Were we in the same friggin class? LOL!
August 26th, 2009 at 9:07 pm
my new school …
my new school teaches it in 9th grade and 11th grade. my old school doesnt, so my first time was in 11th grade. its not too bad. math is my best subject.
August 26th, 2009 at 9:07 pm
just bc someone is …
just bc someone is good at math doesnt mean theyre a vigin.
August 26th, 2009 at 9:07 pm
I loved this video. …
I loved this video. It is very informative. The teacher is patient, and goes through all steps not uming we know it all.
August 26th, 2009 at 9:07 pm
oh lol… well its …
oh lol… well its 4:00pm thursday… kinda late i know
hoping i didn’t fail math.
August 26th, 2009 at 9:07 pm
what school do you …
what school do you go to and where do you live?
maybe we could meet up and study together…im only getting 57!
August 26th, 2009 at 9:07 pm
yeah mine are tmrw. …
yeah mine are tmrw… thursday
and im getting a 54 wish ME luck lol
August 26th, 2009 at 9:07 pm
lol……
lol……
August 26th, 2009 at 9:07 pm
i think we’ve all …
i think we’ve all done this since 6th grde but it comes into play most in 9th grade
August 26th, 2009 at 9:07 pm
this guys a virgin
this guys a virgin