How are Expressions Formed? Video Lecture | Mathematics Olympiad Class 7

hello friends this video on algebraic
expressions part 1 is brought to you by
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topics to be covered in this lesson our
introduction algebraic expressions terms
like and unlike terms factors
coefficients types of expressions
wedding we will talk about monomial
binomial trinomial and polynomial
addition and subtraction of expressions
and finding value of an expression using
algebraic expressions now what do you
think are we going to study under
algebraic expressions so what what is
now you are already aware of what
algebra is all about now here we will
specifically talk about expressions now
let's look at this example let's say
that you have got some number of
chocolate so we didn't do not know the
exact number of chocolates that you have
but you have some number of chocolates
and your little brother has two less
than yours like we do not know the exact
number of chocolates that you have all
your little brother has but all we know
is the number of chocolates with your
little brother is 2 less than the number
of chocolates with you so how would you
express this fact mathematically so you
can write it in a sentence saying that I
have two chocolates more than my little
brother but if I asked you to express
the same thing using a mathematical
expression or how will you explain
explain express this in terms of
mathematics so there we make use of
algebraic expressions let's see how so
we assume that since we do not know the
exact number of chocolates so let's
assume that you have X number of
chocolates so let's see how do we do it
in terms of mathematics so what we will
do since we do not know the exact number
of chocolates with you so let us assume
that you have X number
of chocolates so X is our variable so X
can take any value its can be six its
can be 7 X + 10 X 10 be 200 so let us
assume that you have X number of
chocolates so if you have X number of
chocolates how many chocolates your
brother will have two less than yours
that means he will have X minus two so
you remove two from X so what do you get
with X minus 2 so what does this X minus
2 this is nothing but an algebraic
expression what is this X for that
matter yes it is a variable but at the
same time it is also an expression so
what we exactly mean by expression is
it's a combination of constants
variables operators like plus minus sign
so this is one perfect example or easier
example of expressions you can say you
have a variable X you have a constant 2
you have an operator which is the minus
sign so this is an example of algebraic
expression let's consider another
example and say that use code X and your
friends code twice as you let's say this
is you or let's say this is B and this
is a so let's say that a is code twice
as that of B so if B is 4 10 then is
code 20 if B is 450 then is whole
hundred so basically the score of a is
twice the score of B so how do we
express this in terms of mathematics so
let's assume that B's code X so how much
would a score a would score 2x so what
does this 2x this is also nothing but an
algebraic expressions so these are some
very simple examples of algebraic
expression so with this we can now say
what is an algebraic expression it is a
mathematical phrase with constants
variables and operators like as I told
you that any algebraic expression will
will have a combination of all of these
however it is not compulsory that an
algebraic expression must have constants
variables and operators all of them it
is possible that an algebraic expression
does not have constants it is also
possible that an algebraic expression
does not have multiple operators so all
those things are possible so let us look
at some examples so even before we look
at examples let us quickly recap water
constants variables and operators so let
us first talk about constant so
constants are those which have fixed
values that is their value remains the
same for example let's talk about five
point six so this is the decimal number
but five point six always means five
point six five point six is never equal
to five point seven so this is a fixed
value similarly you think of the numbers
five four - one five six zero twenty
thousand or even three by two which is a
fraction so all of these are numbers and
they have fixed values or something
which is 3 by 2 will always remain three
Bible so the biggest values they have
constant value so they are examples of
constants now let's talk about variables
now variables they do not have a fixed
value their values keep changing they
are generally denoted by alphabets like
X Y Z P Q ABC etc now why are default
variables for example let's talk about X
now this X let's say you have an
equation like this X plus Pole is equal
to 0 and you have another equation where
2x plus 2 is equal to 0 so you have
these two equations now the value of x
in the first equation is minus 4 because
if X is minus 4 then this relation holds
true whereas the value of x in the
second equation is how much it is minus
1 so you see in the first equation the
value of x is minus 4 whereas in the
second
equation the value of x is minus one so
depending upon the situation value of X
changes so X is a variable so we denote
variable using an alphabet book and this
alphabet can pick up different values
depending on different situations the
third one is operator so this operator
includes all the operations like
addition subtraction multiplication and
division these all are operators now let
us look at some examples of algebraic
expressions so let us try to mix and
expressions let's say this is one
expression X plus 4 so you have a
variable you have a constant you have an
operator so X plus 4 is an example of
algebraic expression you have something
like this 3x minus 9 divided by 2 so
here also you have in variables
constants operators so this is an
example of expression something like 10x
it is very simple it what is the meaning
of 10x 10x is nothing but 10 multiplied
by X so you have operator constant
variables so you see these are all
examples of algebraic expressions thank
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