Question
For solving pair of equation, in this exercise use the method of elimination by equating coefficients :$3 x-y=23, \frac{x}{3}+\frac{y}{4}=4$
✓
Answer
$3 x-y=23\ldots(1)$
$\frac{x}{3}+\frac{y}{4}=4$
$4 x+3 y=48\ldots(2)$
Multiplying equation no. $(1)$ by $3$
$9 x-3 y=69\ldots .(3)$
Adding equation $(3)$ and $(2)$
$9 x-3 y =69$
$+ 4 x+3 y =48$
$ 13 x =117$
$x =9$
From $(1)$
$3(9)-y=23$
$ \therefore 27-y=23$
$ \therefore y=27-23$
$ \therefore y=4$
$\frac{x}{3}+\frac{y}{4}=4$
$4 x+3 y=48\ldots(2)$
Multiplying equation no. $(1)$ by $3$
$9 x-3 y=69\ldots .(3)$
Adding equation $(3)$ and $(2)$
$9 x-3 y =69$
$+ 4 x+3 y =48$
$ 13 x =117$
$x =9$
From $(1)$
$3(9)-y=23$
$ \therefore 27-y=23$
$ \therefore y=27-23$
$ \therefore y=4$
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