Any ideas? Please?

Question

Are the following lines parallel, perpendicular, or neither? L1 with equation x – 4y = 20 L2 with equation 4x + y = 4

Answer 1

I tried it out by substituting numbers in for x and y and the lines intersect, but not at a right angle, so they are neither.

Answer 2

L1: x - 4y = 20

=> y = -1/4x - 5 ===> gradient is -1/4

L2: 4x + y = 4

=> y = -4x + 4 ===> gradient is -4

To be parallel, gradient must be the same. To be perpendicular, gradient of 1st line must be (-1/m) of the 2nd line (m).

Both lines' gradients do not satisfy these condition. They are neither parallel nor perpendicular

Answer 3

You have to remember that in order to know if they are perpenticular or parallel you have to know their slope.

First, put your equations in this form:
y = mx + b

Then, look at their slopes
m = slope

If m of L1 = m of L2 ---> lines are parallel
if m of L1 * m of L2 = -1 ---> lines are perpenticular

Answer 4

put them into y=mx+b form...

so x-4y=20
is... y=-1/4x-5

and 4x+y=4
is y=4x+4

so yes they are perpendicular because their slopes are opposite integers

Answer 5

ummmmmmmm i dont know