Posted by sharon on Friday, July 11, 2014 at 8:19pm.
y = 7x  9, 3y = 21x + 7
without graphing, tell whether the graphs of each pair of equations are perpendicular.

Algebra  Barry, Friday, July 11, 2014 at 8:33pm
Dear sharon,
the first equation
y = 7x  9
slope= 7
yintercept= 9
the second equation
3y = 21x + 7
y = 7x (7/3)
slope= 7
yintercept= (7/3)
To determine whether the two lines are perpendicular
slope of equation 1 X slope of equation 2 must be 1.
But in this case,
slope of equation 1 X slope of equation 2 = 49 instead of 1
so the two lines are not perpendicular.
(However, slope of equation 1 = slope of equation 2 and the yintercept of the two equations are not the same, so we know that the two lines are parallel to each other.)
Hope it helps!
Wishing you the best of luck,
Barry

Algebra  Steve, Friday, July 11, 2014 at 8:34pm
the slopes are the same, so they are either parallel or the same line.
If you multiply the 1st by 3, the constant term is different from 7, so the lines are parallel.
Answer This Question
Related Questions
 Algebra  I really don't understand what I am doing. Needing help! With ...
 Algebra (Math)  Without graphing, name the ordered pair where the graphs of the...
 Algebra  Correct me if I'm wrong please 1. Tell whether the lines for each pair...
 Algebra  Tell whether the lines for each pair of equations are parallel ...
 Algebra  Tell whether the lines for the pair of equations are parallel, ...
 Algebra 1  Tell whether the lines for then pair of equations are parallel, ...
 Algebra 1  Tell whether them lines, for each pair of equations are parallel, ...
 Algebra 1  Tell whether the lines for each pair of equations mare parallel, ...
 Algebra  Tell whether the lines for each pair of equations are parallel ...
 Math  38. Tell whether the lines for the pair of equations are parallel, ...
More Related Questions