Question

Use graph paper for this question. Take $2cm=2$ units on $x$-axis and $1cm=1$ unit on $y$-axis.

Solve graphically the following equations:
$3x+5y=12;3x-5y+18=0$
(Plot only three points per line)

• A. $x=-1;y=3$
• B. $x=-1;y=7$
• C. $x=-1;y=5$
• D. $x=-1;y=2$

Answer 1

The correct option is A $x=-1;y=3$

$3x+5y=12$

$⟹3x=12-5y$

$⟹x=\frac{12-5y}{3}$

Let, $y=3$, then $x=\frac{12-5\left(3\right)}{3}=-1$

Similarly,when $y=0,x=4$ and $y=-6,x=6$

$3x-5y+18=0$

$⟹3x=-18+5y$

$⟹x=\frac{-18+5y}{3}$

Let, $y=3$, then $x=\frac{-18+5\left(3\right)}{3}=-1$

Similarly, when, $y=0,x=-6$ and $y=6,x=4$

$\therefore$ the intersecting point is $x=-1,y=3$