Step-by-step explanation:
and I'll explain why so when when we're
looking into combining fractions
positive negative fractions the main
important thing we need to make sure we
have is like denominators
all right common dinar common
denominator the easiest the easiest way
to find a common denominator is to
multiply the denominators right that's
the easiest way to go ahead and find one
just multiply three times eight which is
24 that's gonna give you your comments
and on there does that make sense so
make sense multiply the denominator but
that's not always going to be the least
common denominator so an easy way to
always check to find the least common
denominator is choose the largest
denominator which would be 8 and then
kind of list out the multiples so is and
sitting determine it does 3 divide into
any of those multiples before we get to
24 so just 3 to buy an 8 no so 8 is not
the least common denominator then we go
to 16 just 3 divided into 16 No
24 yes it does so actually end up 3
times 8 is gonna equal 24 and it's okay
lays knowing if you always want to
multiply your denominators you can
always do that but that just because
you're multiplying you're not always
gonna get the least common denominator
and the problem with that is you're
gonna have to simplify your fraction a
little bit more at the end all right but
it is also a way to always get a common
denominator so my lcd is 24 and what I
like you guys to do is always like write
that down so you can always kind of
remember it and basically when we have
an LCD of 24 what we want to be able to
do is say alright what do I need to
multiply now both of my denominators by
to get to 24 well to get 3 forget about
the negative sign per second for do get
3 we need to multiply by 8 right but
there's a problem if you have a fraction
and you only multiply the denominator by
it you've now changed the fraction think
about 1/2 if you have 1/2 and you
multiply the denominator by 3 you now
have 1/6 right is 1/6 equal to 1/2
no so we need to multiply the numerator
and the denominator by 8 think about
again 1/2 times 3 over 3 equals 3 over 6
is 3 over 6 equivalent to 1/2 yes so
when you're multiplying your fraction we
want to make sure we
keep equivalent fractions for 3/8 we
need to multiply by five over five and
then when I multiply fractions I just
simply multiply across numerator times
numerator denominator times denominator
therefore I get negative 8 over 24 plus
I don't know 3 right thank you I don't
know I was like off in my own world I
guess there you go
sorry so therefore now I have negative 8
24 plus 9 over 24 and now when we need
to add combined fractions we need to
combine fractions as long as they have
common denominators we just add or
subtract our numerators so just think
about negative you owe eight dollars you
have nine dollars in your pocket
therefore you're gonna have one dollar
left right and you keep the denominator
the same question okay letting it
internalize
