Q5 of 102 Page 44

Solve the following equations by the method of elimination (by substitution)

4x – 5y = 39


2x – 7y = 51

We have

4x – 5y = 39 …(i)


2x – 7y = 51 …(ii)


From equation (i),


4x – 5y = 39


⇒ 4x = 5y + 39


…(iii)


Substituting the value of x from equation (iii) in equation (ii), we get





⇒ 5y + 39 – 14y = 102


⇒ 39 – 9y = 102


⇒ 9y = 39 – 102


⇒ 9y = -63



⇒ y = -7


Putting this value of y in equation (iii), we get





⇒ x = 1


Thus, we get the solution as x = 1 and y = -7.


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