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all right what I want to do is show you
guys how to find the slope between two
points when we're trying to find the
slope but there's a lot of different
ways that we like to describe slope one
of the most common ones the slope is
rise over run and what we mean by rise
and run is housing how much between two
points how far
what does the distance that your graph
or your change in elevation is risen and
how far is it gone left or right so we
need to go ahead and define that
distance we need to find the change so
let's go work slow very commonly
referred to as rise over run and what
does that really mean what is really the
rise of run well what that really is is
to change all right as Delta Y over
Delta X and what this means is the
change in Y over the change in X well
that's kind of craziness why would give
me a better thing any better way to
write that all right well if we have two
points we can label we have two points
we can label our points x1 y1 and y1 x1
y1 and x2 y2 so I'm gonna look at these
two points and I'm going to go ahead and
label them it doesn't matter how you
want to label left which one's x1 and
which ones x2 what I'm going to say this
one be x1 this one's like - oh hi
everyone
this one is x2 and this one is y2
so would you because you remember on a
coordinate point you have your X and
your Y your X in your life however you
can't both label these X Y so we use
subscripts to differentiate between the
two points all right so now if I know
that my slope is the change in Y over
the change in X all I'm going to do now
is just like we learned it before to
improve now we're just going to evaluate
and plug in our values into our equation
for slope all right so I'm going to take
my Y 2 which is a negative 8 minus y1
which is 4 all over X 2 just 3 minus 1
foot in parentheses a negative 1
remember I'm going to keep those
parentheses just to make sure that I'm
not making any mistakes making any
mistakes with my negatives so negative 8
minus 4 is become a negative in 12 and 3
minus a negative 1
these are going to to the two negatives
are going to cancel each other out and
it's going to become a positive positive
or negative 12 divided by 4 now becomes
a negative 3 so therefore our slope is a
negative 3 and a lot of times just let
you guys know a lot of times when you're
graphing like a negative 3 you need to
say oh well it's not in it's not the
rise or a run what's the rise or run
well remember we can always keep that
whatever you need to change a whole
number if your whole number is your
slope and you always need to have it at
in a fractional form just remember you
can always put it over one guys
that's your fractional form but it means
the exact same bet all right so that's
how you find the slope between two
points
you
