For the pairs of lines defined by the following equations indicate with an "I" if they are identical, a "P" if they are distinct but parallel, an "N" (for "normal") if they are perpendicular, and a "G" (for "general") if they are neither parallel nor perpendicular.

Question

For the pairs of lines defined by the following equations indicate with an "I" if they are identical, a "P" if they are distinct but parallel, an "N" (for "normal") if they are perpendicular, and a "G" (for "general") if they are neither parallel nor perpendicular. 
 3x+4y+5=0 and 6x+8y+10=0. 
 3x+4y+5=0 and 3x+4y+7=0. 
 3x+4y+5=0 and 3x+5y+7=0. 
 −4x+3y+5=0 and 3x+4y+7=0.

Steve · Answer

the slope of the line Ax+By+C=0 is -A/B

so, check the pairs.

#1 -3/4 vs -6/8 same, so parallel or identical
since multiplying the 1st by 2 gives the 2nd exactly, they are in fact the same line.

do the others in like wise.