Question

If line $3x+4y+c=0$ lies midway between $3x+4y+10=0$ $\&$ $3x+4y-10=0$ then value of $c$ is

• A. $0$
• B. $10$
• C. $20$
• D. $-10$

Answer 1

The correct option is A $0$

$3x+4y+10=0\to \left(1\right)3x+4y-10=0\to \left(2\right)$

line passing through midway between $\left(1\right)$ & $\left(2\right)$ is

$3x+4y+\frac{10-10}{2}=0$

$3x+4y+0=0$

Given $3x+4y+c=0$

$\therefore$ , $c=0$