Q. 44.2( 25 Votes )

Solve the following simultaneous equations.
i.

ii.

iii.

Answer :

(i)




4x + 3y = 48 eq.[1]




2x - 3y = 4 eq.[2]


Adding eq.[1] and eq.[2], we get


4x + 3y + 2x - 3y = 48 + 4


6x = 52



Using this in eq.[1], we have




104 + 9y = 144


9y = 40



(ii)




x + 15y = 39


x = 39 - 15y eq.[1]




4x + y = 38


Using eq.[1], we have


4(39 - 15y) + y = 38


156 - 60y + y = 38


59y = 118


y = 2


Putting this value in eq.[2]


x = 39 - 15(2)


x = 39 - 30


x = 9


(iii)




2y + 3x = 13xy eq.[1]




5y - 4x = -2xy eq.[2]


Multiplying eq.[1] by 4 both side, and Multiplying eq.[2] by 3 both side, we get


8y + 12x = 52xy eq.[3]


15y - 12x = -6xy eq.[4]


Adding eq.[3] and eq.[4]


8y + 12x + 15y - 12x = 52xy - 6xy


23y = 46xy


1 = 2x



Putting this in eq.[1]







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