Maths Simple Equation part 4 (Questions: Setting up Equation) CBSE Class 7 Mathematics VII Video Lecture | Extra Documents & Videos for Class 7

hello friends this video on simple
equations Pat Forde
is brought to you by exam for calm no
more fear from exam so based on whatever
we have learned about the basics of
simple equations let us try to solve
some questions question number one check
whether the value given in the brackets
is the solution to the given equation or
not now even before we start trying this
let us first try to understand what do
we mean by solution of an equation so
solution of an equation means that value
of the variable which when put in place
of the variable the equation will be
true that means let let us look at the
first example so the first example is 7
n plus 5 is equal to 90 so a solution of
this equation would be such a value of n
for which LHS is equal to RHS so that
value of n for which whatever where do
you get from 7 n plus 5 should be equal
to 19 only then that is called solution
of this equation right so here the value
that is given is minus 2 so let us put n
is equal to minus 2 so LHS what would be
a legend salacious would be 7 into minus
2 plus 5 so this is equal to minus 14
plus 5 which is equal to minus 9 and
what is the value of the RHS RHS is 19
so what do we see we see that LHS is not
equal to RHS so do you think that M is
equal to minus 2 is a solution no this
is not a solution of this equation let
us try with the next one
which is for P minus 3 is equal to 13
so here the solution that is given as P
is equal to 0 so let us put P is equal
to 0 in LHS it becomes 400 0 minus 3
which is equal to 4 into 0 0 so 0 minus
3 is minus 3 and what is the value on
the
that is 13 so in this case also we see
that NHS is not equal to RHS so what do
you think is P equal to 0 solution of
this equation no this is also not a
solution of this equation question
number two right equations for the
following statements the sum of numbers
x + 4 is 9 sum of numbers that means
when you add these numbers X and 4 that
is X plus 4 then what is the result
there is are this 9 so this would be the
equation for the statement 3/4 of T is
15 3/4 what do we mean by 3/4 it means 3
by 4 or of something 3 by 4 multiplied
by something what is that something that
something is the variable T so 3 by 4 of
T is equal to 15 if you take away 6 from
6 times y you get 16 so if you take
every 6 seconds you are removing 6 from
6 times y so basically you are
subtracting 6 from 6 times y and what do
you get you get 16 if you add 3 to
one-third of Z so how do you write
one-third of Z it is nothing but 1 by 3
of Z so you add 3 to 1 by 3 of Z and
what do you get you get 13 so Z by 3
plus 3 is equal to 13 so this is how we
convert statements into equations
question number three write the
following equations in statement forms
ok so this is just the opposite thing
not so the first one is 3p plus 4 is
equal to 25 so what are we actually
doing here we are adding 4 to 3 times P
so that means 4 added to 3 times P
gives what gives 25 similarly in the
second one what are we doing we are
adding two to half of T so two added to
half of P gives eight in the third one
what are we doing are we adding
something no we are subtracting
something that means to subtract it from
four times P or we can say to taken away
from four times P so to subtract it from
four times P gives 18 so these are
pretty simple so you just need to
understand what do you mean by a
specific linear equation question number
four set up an equation in the following
cases it 1 says that he has seven
marbles more than five times the marbles
permit has if one was 37 mumbles take em
to be the number of permits marbles okay
so this is something which we had
discussed so as per our step 1 permits
marbles is something that we do not know
so we assume it to be a variable now
here is the question it sees that let's
assume it is M of it now the our second
condition is to establish the criteria
so what is the criteria if one has seven
marbles more than five times per means
marbles so five times of permits marbles
would be five M plus seven 7 more so
five M plus seven should be advanced
models but actually if one has how many
marbles
he has thirty seven marbles therefore
five M plus 7 is equal to 37 would be
the equation let's look at the next one
the teacher tells the class that the
highest marks obtained by his student in
her class is twice the lowest marks plus
7 the highest score is 87 so we already
know the highest score so what we do not
know
the lowest score so let us assume the
lowest score to be L so our step one is
done what is going to be step two in
step two we are going to establish the
relationship so in step two we would say
that what is going to be our highest
marks so highest marks would be twice
the lowest marks plus seven so twice the
lowest marks that is 2l plus seven and
finally in step three what are we going
to do we are going to set up the
equation so we are going to equate these
this highest mark that is 2n plus 7/2
how much the given highest score that is
87 so 2n plus 7 is equal to 87 would be
the equation thank you please visit exam
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