Let line 1 be the graph of 5x+8y=-9. Line 2 is perpendicular to line 1 and passes through the point (10,10). If line 2 is the graph of the equation y=mx+b, then find. m+b
1. First convert from standard form to slope intercept form .
$5x+8y=-9$
$8y=-5x-9$
$y=-5/8-9/8$
$m=-5/8$
2. find other line
Perpendicular lines have negative reciprocal slopes
$-5/8 =>8/5$
$y=8/5x+b$
From the given information,
$(10)=8/5(10) + b$
$10=16+b$
$b=-6$
the line is:
$y=8/5x-6$
therefore 8/5-6=$-22/5$
1. First convert from standard form to slope intercept form .
$5x+8y=-9$
$8y=-5x-9$
$y=-5/8-9/8$
$m=-5/8$
2. find other line
Perpendicular lines have negative reciprocal slopes
$-5/8 =>8/5$
$y=8/5x+b$
From the given information,
$(10)=8/5(10) + b$
$10=16+b$
$b=-6$
the line is:
$y=8/5x-6$
therefore 8/5-6=$-22/5$
