Solving an Equation Video Lecture | Extra Documents & Videos for Class 7

so how do you maintain the bath how do
you maintain the bats let's get rid of
this equation let's do some fun stuff
let's put some pebbles let's put some
pebbles of equal weights let's say all
1kg pebbles on this pad and 1 kg pebbles
10 of them on this path so you have ten
of them on this path and ten of them one
the Spanish were perfectly balanced both
sides are perfectly balanced now let's
see I remove a pebble from this pad I
remove a pebble from what is going to
happen the weight on this side is higher
this side is going to start tilting down
and then something is going wrong right
he said the one key rule to solving an
equation is that it should always be
perfectly balanced how can i balance it
as remove one stone from this pan as
well I will remove one stone from this
pan as well
now it's perfectly balanced again it's
perfectly balanced again okay suppose I
remove two stones from this pan why do I
need to do I need to remove two stones
from this panel again it's perfectly
balanced I put one stone on this what do
I need to do this is start going low I
need to put one stone up this package
what am I trying to do you're wondering
I came I started this thinking I'm going
to learn equations why I'm trying to
balance patch this is obvious right
everything we did here seemed obvious
there is actually teaching you the basic
principle the only principle required to
solve any equation what did we do when I
took two pebbles out from here I took
two pebbles out from here as well when I
put one pebble back in here
I put one pebble back in here as well
what was I doing in very simple words
whatever I do to this path whatever I do
to this path I need to do to this pan as
well okay it is what I want to if I
remove two I remove two if I put one I
put one so whatever you do to one pan do
it to the other pan as well if you do
that it will remain perfectly balanced
that is exactly what you do in an
equation you have two sides of an
equation whatever you do to the
left-hand side to the exact same thing
to the right-hand side
whatever you do to the left-hand side of
an equation do the same thing to the
right hand side of the image your
equation will always stay
perfectly balanced same as say what you
do to one side of the pan to the same
thing to the other side of the path and
the your balance your beam balance is
not perfectly balanced skater so that's
how you solve equations as simple as
that
so let's say I take an equation 2x plus
5 equal to 10 right 2x plus 5 equal to a
now I need to find the value of x right
my X is only on the left hand side I
have 2x plus 5 here and I have n on the
right hand side so your aim should be
finally you want to be left with if you
imagine this as two sides of the pan you
finally want to be left with X and one
pan and a number in the other correct
because what will they tell you that X
is equal to that number if I have X in
this pan and a number in this pan it
tells me X is equal to this number
because my back beam balance is
perfectly balanced so from the left hand
side you need to get rid of everything
other than X so that you are left with
only X here and you're left with only a
number so let's start getting rid of
stuff from the left hand side and we
know the one rule so that the pans are
perfectly balanced keep imagining a pan
when you do think only on one side you
should mentally imagine the pan going
down on the other side so you know
something's going wrong right so
whatever you do on the left-hand side do
the same thing on the right so who x
plus y equal to 10 we want to get rid of
the 5 how can I get rid of the 5 I have
a plus 5 how do I get rid of the plus if
it becomes 0 if it becomes 0 means it's
gone right
if it becomes 0 means it's gone how will
the plus 5 become 0 we call the first
chapter where did you learn in rational
numbers negative of a number if you take
a number and it's negative you add them
you get 0 right so take 5 add it's
negative if I want to make + 5 0 I need
to put a minus so I have 2x + 5 here
I'll put a minus 5 so then this is going
to become 0 if I put a minus Phi on this
side I need to put a minus 5 on this
side right so this plus Phi minus Phi
becomes 0 this is gone n minus 5 becomes
5 so now I have 2x equal to 5 I don't
want it to I want to get rid of the 2
how will I get rid of the 2 2 X if I
divide it by 2
if i / which is nothing but the recipe
book right two's reciprocal is 1 by 2
I'm multiplying it by 1 by poor dividing
it by 2 to get rid of it so if I divide
it by 2 here I'll divide it by 2 here as
right so I have 2x by 2 5 by 2 2 X by 2
the 2 gets cancelled I'm left with 8 5
by 2 here 5 by 2 and left with 2 point 5
so X equal to 2 points that's your as
simple as that
it's all this is all that solving
equations was about there is nothing
else to it that's it your aim is to be
left with only X on one side and only a
number on the others right because then
the two pans are balanced then X is
equal to the number that means you know
the value of x and the only rule there's
only one root which is whatever you do
on the left hand side you need to do on
the right hand side ask and it's done
that's all that we need that is all that
it takes to solve the equation