L2 : Algebra - Algebra, Mathematics, CBSE Class 6 Video Lecture

hello friends this video on algebra part
two is brought to you by exam Fuhr calm
no more fear from exam so what is
algebra it is a branch of mathematics in
which letters or symbols are used to
represent numbers or quantities in
4,000,000 equations to help in problem
solving now as you move on to your
higher classes you would see that there
are certain problems which are not so
simple that they can only be solved with
numbers so let me give you an example in
this case so a problem which cannot be
solved only with numbers not very easy
to solve only with numbers so this is
your elder brother and this is you now
we are talking about your edges now
let's see that the elder brother see is
that the younger brother is six years
younger than me so he says that he's six
years younger than me perfect he also
says that I will be fifteen years old
after five years so now he is clearly
not telling what is his current age he
is also not telling how old his brother
is he is only telling that he is six
years younger to me and after fifteen
years my age will be fifteen so these
are the only two relation ships which is
given in this problem now let's say that
the problem statement is you will have
to find out the current ages of the two
brothers now I don't say that you can
not do it only with numbers you can do
it with numbers also but when these like
this is just one example of a problem
but when these kind of problems become
more complex and let's say that instead
of the second statement if you see is
that after five years my age will be two
times my brother's age so in those kind
of complex situation it becomes all the
more difficult to only deal with numbers
only by additions
attraction multiplication of numbers you
cannot solve such problems so for
complex problem solving we make use of
these alphabets the letters and we
assume those letters to have certain
value and then we solve the entire
problem so let us look at this case in
this problem how do we approach it so
let us assume that the current age of
the elder brother is X so X is an
alphabet it is not a number but we
consider X as a number in this case
because we are assuming that the age of
the elder brother is X and therefore as
per the problem what would be the
youngest brother age he is six years
younger than the ender brother so his
age would be X minus six that's quite
obvious so this X and X minus six we
have assumed right but we in this in
order to solve this problem we need to
find out the value of x that what is
that exact value or what is the exact
number that X will be so as per the
question again it says that after 15
years after five years so after five
years as per our assumption age of the
elder brother should be X plus five
right after five years his age would
increase one every year so it should be
X plus five but in the problem it is
given that has ages 15 after five years
so that means this X plus five is equal
to 15 so by solving this equation so we
have actually build an algebraic
equation because why this is algebraic
equation because this equation has
numbers it has the Equality sign and it
also has alphabets so this is an
algebraic equation so now when we solve
this equation we get the value of x and
the moment we get the value of x our
problem is solved so this is one example
to tell you that why do we need algebra
and how do we use algebra to solve
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