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NCERT Exemplar Solutions Class 8 Mathematics Solutions for Linear Equations in One Variable - Exercise in Chapter 4 - Linear Equations in One Variable
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If (5x/3) – 4 = (2x/5), then the numerical value of 2x – 7 is
(a) 19/13
(b) -13/19
(c) 0
(d) 13/19
Answer:
(b) -13/19
Given, (5x/3) – 4 = (2x/5)
(5x/3) - (2x/5) = 4
LCM of 3 and 5 is 15
(25x – 6x)/15 = 4
19x = 4 × 15
19x = 60
X = 60/19
Then, Substitute the value of x in 2x -7
= (2 × (60/19)) – 7
= (120/19) – 7
= (120 - 133)/19
= - 13/19
Video transcript
"hello students i am rita your math
leader tutor and the today's question is
if 5x by 3 minus
4 is equal to 2x
by 5 then the numerical value of 2x
minus 7
is the option is 19 by 13 b is minus 13
by 19
c is 0 and the option d is 13 by 19.
first of all we solve this equation
5x minus 3 first
we separate out the variable and
constant term
minus 4 when it goes there by the
process of transposition it becomes
plus now the lcm
of 3 and 5 is 15 so 3 5's are 15 5
5's are 25 x minus 5 3's are 15
then two 3's are 6
is equal to 4
now we cross multiply here
by applying cross multiply so 25
minus 6 it becomes 19x
and 15 into 4 it becomes
60 now the value of x
is equal to 60 by
19 so this is the value of x
but in the question we have to find the
value of 2
x minus 7 so we put the value of x
2 into 60 by 19
minus 7 by 1 so it becomes
120 by 19 minus 7
by 1 calcium is 19
so 120 minus
19 into
7
so it becomes 120 minus
133 so it becomes
minus 13 by 90
so this is our answer minus 13 by 19 it
means
option b is correct so
minus 13 by 19 this is our answer i hope
you like this video so please subscribe
lido for more updates and do comment
your questions thank you"
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