Question

Points $(1,2)$ and $(-2,1)$ are

• A. on the same side of the line $4x+2y=1$
• B. on the line $4x+2y=1$
• C. on the opposite side of $4x+2y=1$
• D. None of these

Answer 1

Answer: (C)

on the opposite side of $4x+2y=1$

Given equation of line is
$L=4x+2y-1=0$
For the point $(1,2)$, $L=7>0$
For the point $(-2,1)$, $L=-7<0$
Opposite signs shows that the two points lies on the opposite side of the line $L=0$.