SOLUTION: Tell whether the lines for the pair of equations are parallel, perpendicular, or neither. y = (-1/3)x – 5 -18x + 6y = 21

Algebra ->  Coordinate-system -> SOLUTION: Tell whether the lines for the pair of equations are parallel, perpendicular, or neither. y = (-1/3)x – 5 -18x + 6y = 21      Log On


   

Question 408915: Tell whether the lines for the pair of equations are parallel, perpendicular, or neither.
y = (-1/3)x – 5
-18x + 6y = 21
Found 2 solutions by ewatrrr, MathLover1:
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

 



Are these lines parallel, perpendicular, or neither:

y = (-1/3)x – 5                |m = (-1/3)

-18x + 6y = 21 OR y= 3x+21/6   |m = 3

Lines are ⊥, having slopes that are negative reciprocals of one another

Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
y+=+%28-1%2F3%29x+%96+5...this is the slope-intercept form and we can say that slope m=%28-1%2F3%29%7D%7D+and+y-intercept+is+%7B%7B%7B-5

-18x+%2B+6y+=+21...write this equation in the slope-intercept form too
6y+=18x+%2B+21
6y%2F6+=18x%2F6+%2B+21%2F6
y+=3x+%2B+3.5.........we can say that slope m=3%7D%7D+and+y-intercept+is+%7B%7B%7B3.5
so the slopes of our lines are m=%28-1%2F3%29%7D%7D+and+%7B%7B%7Bm=3%7D%7D%0D%0A%0D%0AIf+%7B%7B%7B2 lines are parallel they have the same slope; evidently, these two lines are not parallel.
If they are perpendicular, their slopes multiply to get -1;
so m1+=+-1%2Fm2
let's check it:
-1%2F3+=+-1%2F3.........they are perpendicular
let's see their graph:

+graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+3x%2B3.5%2C+-0.33x-5%29+