More quadratic formula.
Let's rock first let's just make sure we
have a good pen size. Oh
definitely not that's way too small.
Okay let's see what we got here. So
we've done some quadratic formulas,
let's make them look a little weirder
here.
How about three x squared 
minus four x minus
six is equal to
negative three.
Why not ,okay so three x squared minus
four x minus six is equal to negative
three, I can't do anything right away.
First thing we have to do is make it
equal to
zero. I always always always make it
equal to zero does not matter if this is
minus three x plus seven or minus three
x squared.
You know have everything over
there, just move everything over to that
left side make it so it's equal to zero
and then plug everything into the
quadratic formula. Okay so we're getting
rid of this negative three by adding
three to both sides.
It gives us three x squared minus four
x minus three
is equal to zero. Much better. See now
that we could actually work with
because it's equal to zero. pPlugging it
in
to our quadratic formula again if we do
not remember it
remember it x equals negative b
plus or minus the square root
of b squared minus 4ac
all over 2 a that's a c
all right so we plug our numbers in
there plugging in our a which is
3 our b which is that negative 4 and our
c which is the negative
three okay so we got x is equal to
negative b negative negative four
plus or minus not really writing too
good today
um b squared hey put this in parentheses
always use parentheses when you're
plugging in for these uh it will
remind you that you are doing negative 4
times negative 4
to give you positive 16 and you're not
doing negative 4 to the second power
which would give you a negative
16. so just be really careful with that
we have minus
four times a a's value which is that
three again i forgot i can't point at
the screen you can't see my fingers
um four times a which is three times c
which is that number at the end there
now negative three
all over two times a or two times
three okay now we can move down a little
bit here
bam let's simplify some stuff so we have
x is equal to negative negative four is
now a positive four
plus or minus a here we have the
negative 4 squared solve this part first
negative 4 squared negative 4 times
negative 4
is a positive 16. there we go
and then here um my personal weight
again i like to think of this
as being a negative 4. okay
you don't have to so i look at it as
negative 4
times 3 which is negative 12
and then i'm taking negative 12 and i'm
multiplying it by negative 3
which gives me a positive 36 so this is
going to be
plus 36
and this is divided by 2 times 3 which
is 6.
hey if you don't want to think of it as
being a negative 4 don't if you just
want to think of it as being 4
it's fine 4 times 3 is 12 12 times
negative 3 is negative 36
but you are minusing a negative 36 which
will give you that plus 36
okay so just whatever way you think is
easiest
all right um combine these two numbers
16 and 36 together
so we've got x is equal to 4 plus or
minus square root of 52
over 6. right the previous one i said it
was perfectly fine to leave it as a
square root but
sometimes it is going to ask you to go
to the nearest like hundredth of the
nearest tenth or whatever it may be okay
so
i am going to kind of show you that real
quick okay so it does ask
to keep it into radical form radical
form is meaning to leave it as a square
root
if it says to put it into a decimal to
the nearest tenth
nearest hundredth then you'd actually
have to solve what the square root of 52
would be
so let's do a little square root of 52
on here
okay if you're doing it on your phone
you just click 52 oh there you are
52 and then you press the square root
button which should be the little thing
right there
a square root and it gives you an answer
of seven point two one one one
zero okay um so if it says nearest
hundredth
just round this off to the nearest
hundredth okay so it'd really be x is
equal to and then we got 4 plus or minus
instead of being the square root of 52
we are replacing it
again with that number of 7.21
and that is divided by 6. but we want
our two answers for this because we
actually want the solutions
so one of our answers is going to be x
is equal to
4 plus 7.21
divided by six and our other answer is
going to be
four minus seven point two one divided
by six
i should do four plus seven point two
one gives us
11.21
divided by six and it's perfectly fine
you don't have to use the full number
you could round it off to the nearest
hundredth
and just use the seven point there you
go
seven point two one on there so you use
7.21
plus 4 gives you 11.21 and divide that
by
6 and it is going to give you that
really long number that you have on
there
1.8683 blebleblade over and over again
okay if it says to nearest hundredth i'm
okay with 1.86 i'm okay with 1.87
okay whatever way you want to go if you
want to round up round up if you don't
run
don't you just don't round up i don't i
don't really care okay
so we're going to write down a 1.87
we'll
round that up because it is a higher
than a five on there
there you are one point eight six eight
if it was one point eight six one i
would probably work one point eight six
uh since it is that five or higher round
it up
okay so we do the same thing on here we
do our 4 minus 7.21
gives us that negative 3.21 and then we
are going to divide that number by 6
and gives us a much nicer number on
there
negative 0.535 it does say to the
nearest hundredth
in my little head that i said at the
beginning okay so we are going to go
with
the negative point three two one divided
by
six let me write that in there uh so we
have negative
point five three five so we will go with
negative and then point five four
if you want to write oh i missed the
negative there we go that's a negative
in there
just get rid of this one there we go
okay so that is a negative sign um
it is negative 5.35 so i just rounded it
up to negative
0.54 if you wrote 0.5 negative 0.53
again that's fine okay so if it does say
to put it to the nearest hundredth
round it to the nearest hundredth two
decimal places it says around the
nearest tenth
one decimal place really that's the only
ones i'm going to use could be thousands
could be ten thousands and all that kind
of stuff but usually it's just one or
two decimals
tenth or hundredth okay um if it says
leave it in radical form then you would
use
your square root of 52 and you would
just use
4 plus the square root of 52 divided by
6
and 4 minus the square root of 52
divided by 6.
okay so it depends on the wording of the
problem as to how it's going to be
written
if it says in radical form leave it as a
square root of 52
if it says to write it as a decimal then
actually write them out as the decimal
is on there
if it's a perfect square root always do
it okay so if this was the square root
of say 49
solve that okay add a seven okay um
so if you ever get a perfect square root
always just kind of wipe that out
regardless
it's just always going to happen don't
leave it as the square root of 49
because that can be simplified more
okay and then if you ever get an answer
on here that can reduce down like
you know if this was say 4 plus 8 you
know divided by six
do four plus eight and then divide that
by six don't don't leave it as twelve
over six or something like that reduce
things down
okay um but we're doing it just as
decimals so decimal answer is
one point eight seven and negative point
five four all right let's do that
okay just another different example of
quadratic formula
when it is not equal to zero again it
could be anything you could pop an x on
here it doesn't matter just move the x
over
put an x squared on there move it over i
always always always make it equal to
zero okay um
questions on anything let me know
