Question
Solve the following simultaneous equation.
5x + 2y = –3; x + 5y = 4
5x + 2y = –3; x + 5y = 4
✓
Answer
$5 x+2 y=-3 \ldots(I)$
$x+5 y=4 \ldots( II )$
Multiply Eq. I by 5 and Eq. II by 2
$25 x+10 y=-15 \ldots(III) $
$2 x+10 y=8 \ldots(\text { IV) }$
Change sign of Eq.(IV)
$25 x+10 y=-15 $
$\underline{-2 x-10 y=-8}$
$23 x=-23$
$x=-\frac{23}{23} $
$x=-1$
Subsituting $x=-1$ in Eq.II
$-1+5 y=4 $
$5 y=4+1$
$5 y=5$
$y=\frac{5}{5}$
$y=1$
∴ solution is (x, y) = (–1, 1)
$x+5 y=4 \ldots( II )$
Multiply Eq. I by 5 and Eq. II by 2
$25 x+10 y=-15 \ldots(III) $
$2 x+10 y=8 \ldots(\text { IV) }$
Change sign of Eq.(IV)
$25 x+10 y=-15 $
$\underline{-2 x-10 y=-8}$
$23 x=-23$
$x=-\frac{23}{23} $
$x=-1$
Subsituting $x=-1$ in Eq.II
$-1+5 y=4 $
$5 y=4+1$
$5 y=5$
$y=\frac{5}{5}$
$y=1$
∴ solution is (x, y) = (–1, 1)
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