Question

if 3x+7y=13 and zx+8=3y is parallel, find the value of z

Answer 1

line 1: 3x+7y=13 or 7y=-3x+13, or y=(-3/7)x +(13/7)

slope=-3/7, so all lines with same slope R parallel

y=-(3/7)x+sumthun

Answer 2

if 3x+7y=13 and zx+8=3y is parallel, find the value of z =

Well the first number that x is thought to be can be 2 and y can be 1

So 3x+7y=13 works as

3x=6 + 7y=7 work out to be 13

However in the next equation stating that zx+8= 3y it becomes dicey as

3y = 3 and - 8= -5  which doesn't work as x = 2 so z= -2.5 which is not close to parrellel

However if x = -12 and y= 7 then 3x= -36 + 7y= 49 =13 so that part's right and then

zx+8= 3y can be 3y =21 and -8 =13 so x= -12 and z= 13/-12 which is as close to parallel as you can hope to get without getting the equation to complicated!

Answer 3

Let's find the gradients of the two lines:

y=(13-3x)/7 and y=(zx+8)/3. The gradients are -3/7 and z/3.

To be parallel, these gradients must be the same so z/3=-3/7, z=-9/7.

[This would make the second equation -9x/7+8=3y or -9x+56=21y which can also be written 9x+21y=56.]