Question 12 Marks
Solve the following simultaneous equation.
$49x – 57y = 172; 57x – 49y = 252$
$49x – 57y = 172; 57x – 49y = 252$
Answer
View full question & answer→$49 x-57 y=172 \ldots$
$57 x-49 y=252 \ldots$
Adding both the Equations
$49 x-57 y=172 $
$57 x-49 y=252 $
$----------$
$ 106 x-106 y=424$
Dividing both sides by 106
$x-y=4$
Subtract equation (I) and (II)
$49 x-57 y =172 $
$-57 x+49 y =-252 $
$----------$
$-8 y-8 y =-80$
Divide both sides by $(-8)$
$x+y=10$
Equating Eq. (III) and (IV)
$x-y=4$
$\frac{x+y=10}{2 x=14} $
$x=\frac{14}{2} $
$x=7$
Substituting $x=7$ in Eq. IV
$7+y=10 $
$y=10-7$
$y=3$
$\therefore$ solution is $(x, y)=(7,3)$
$57 x-49 y=252 \ldots$
Adding both the Equations
$49 x-57 y=172 $
$57 x-49 y=252 $
$----------$
$ 106 x-106 y=424$
Dividing both sides by 106
$x-y=4$
Subtract equation (I) and (II)
$49 x-57 y =172 $
$-57 x+49 y =-252 $
$----------$
$-8 y-8 y =-80$
Divide both sides by $(-8)$
$x+y=10$
Equating Eq. (III) and (IV)
$x-y=4$
$\frac{x+y=10}{2 x=14} $
$x=\frac{14}{2} $
$x=7$
Substituting $x=7$ in Eq. IV
$7+y=10 $
$y=10-7$
$y=3$
$\therefore$ solution is $(x, y)=(7,3)$