Q. 115.0( 1 Vote )

Equating the coef

Answer :

As the name holds, method of elimination literally uses elimination technique.

We have,


3x – 7y + 10 = 0


3x – 7y = -10 …(i)


y – 2x = 3 …(ii)


In order to eliminate one of the variables (x and y), we need to make that variable’s coefficient equal in both of the equations.


In this question, it is easy to eliminate y, since both the equations have different signs for variable y. That is, equation (i) has a (-) sign before y and equation (ii) has a (+) sign before y.


Now, we need to make the coefficient of y equal, since in equation (i), y’s coefficient is 7 and in equation (ii), y’s coefficient is 1 (ignoring the signs before it).


For equal coefficient of y, multiply equation (ii) by 7. (Multiplication has to be done over the whole equation as to balance the equation even after making changes)


So, we have from equation (ii),


y – 2x = 3 [× 7


7y – 14x = 21 …(iii)


Now, we have equations (iii) and (i) which can be solved by eliminating variable y.


Recall equation (i) and (iii),


3x – 7y = -10


7y – 14x = 21


Solve these,



We get,


-11x = 11



x = -1


Put this values of x in equation (ii), we get


y – 2(-1) = 3


y + 2 = 3


y = 3 – 2


y = 1


Thus, we get our solution as x = -1 and y = 1.


Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Related Videos
Equations of MotionEquations of MotionEquations of Motion41 mins
Structural Organisation In Animals-IIStructural Organisation In Animals-IIStructural Organisation In Animals-II57 mins
Structural Organisation In Animals-IStructural Organisation In Animals-IStructural Organisation In Animals-I54 mins
Master Mole Concept in 45 MinutesMaster Mole Concept in 45 MinutesMaster Mole Concept in 45 Minutes48 mins
Variation in g with Rotation of EarthVariation in g with Rotation of EarthVariation in g with Rotation of Earth42 mins
Significance of Newton's Laws in daily lifeSignificance of Newton's Laws in daily lifeSignificance of Newton's Laws in daily life42 mins
Variation in g due to Height and DepthVariation in g due to Height and DepthVariation in g due to Height and Depth33 mins
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses