Additive Inverse of Rational Number (Part - 14) - Rational Numbers , Maths, Class 8 Video Lecture

hello friends this video on rational
numbers part 14 is brought to you by
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unsimilar lines now we will learn about
negative of example that is how do we
find negative over the world what is
negative of a number so it is basically
that number which when added to the
number gives us zero so let us say we
have a number a rational number in the
form P by Q so what does that number
which when added to P by Q will give you
zero so let us say that number is some
number X so what would be the value of x
this H will be nothing but minus P by Q
because P by Q minus P by Q is what
nothing but zero so basically if you add
minus P by Q 2 plus P by Q you get a
zero so we can say that minus P by Q
this is negative of plus P by 2
so finding negative of a number is very
split is simple all you need to do is
you just need to reverse the sign and
this negative of a number is also known
as the additive inverse so why is it
called additive inverse because in this
case again the science and reversing
surplus is becoming minus minus is
becoming plus so therefore inverse and
by additive because your on addition of
the two numbers you get a 0 so that is
why it is called additive inverse so
please remember that additive inverse is
the negative and multiplicative inverse
is the reciprocal so again similarly 0
is called the additive identity because
you take any rational number and when
you add a 0 to it what do you get you
get the same number so if this is a
rational number you add a 0 to it you
would again get the same number so that
is why 0 is going to additive identity
because when you add this to a 1 / the
number is able to retain its identity
like when you multiply 1 to a number a
number is able to retain its identity
- the multiplicative identity that is
during multiplication it helps the
number to retain its value
similarly zero helps the number to
retain its value during addition so 0 is
called additive identity so you think of
any number like 2 by 3 plus zero this
would give you 2 by 3 you think of minus
6 by minus 8 plus 0 this would give you
minus 6y minus 8 which is nothing but 6
by 8 and these are the same things so
basically any number when added to 0
even when one is added to 0 what you get
you get 1 so the identity is retain so
let us again try to find out few
negatives of the numbers so here you
have 51 so what would be negative or 51
what does that number which one added to
51 will give you 0 nothing but minus 51
10 by 24 its negative would be minus 10
by 24 minus 11 by 6 for this what would
be the negative so this it's negative
would be again the opposite signs right
now it has a minus sign so it would
become plus 11 by 6 so negative of minus
9 by minus 3 the here you have something
interesting here you have minus 9 by -3
minus 9 by minus 3 is same as 9 by 3
those minus and minus will cancel out so
it is 9 by 3 so basically you have to
find out the negative of mine by T we do
which would be minus 9 by 3 so this is
the negative of this number now this is
important because many a times you might
think that okay mine is 9 by my industry
and just change the sign when you say
that the negative of minus 9 by minus 3
is 9 by 3 but that is incorrect because
minus 9 by minus 3 is nothing but 9 by 3
this minus and minus will cancel out and
negative of 9 by 3 is minus 9 by 3 so a
few things with regards to these sign
conventions which you should always
remember not only with regards to
finding out negative but in general also
for calculation so whenever you have 2
minus
like let's say you have something like
minus nine by minus three so he's my
usual cancer and this will become equal
to 9 by 3 now if you have something like
minus 9 by 3 this is the same as 9 by
minus T it means the same thing right so
these are few things which you should
always remember
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