Finding Equations of Lines, Given a Parallel or Perpendicular Line, Using Slope-Intercept Form

[agentkelli93]

When you are solving these kinds of equations, when you write the equation for the line is it supposed to be like you only write the slope's and y-intercept's values? Example: y= -3x+18, because even in class we were doing that, but I didn't really understand why.

[Ahmedtw5]

@georgewoodbury why did u add 1 to both sides

[georgewoodbury]

@Ahmedtw5 If you have 9 = -1 + b, you need to isolate b. That means you need to move 1 to the right side. To move the -1 to the right, you add 1 to both sides, because -1+1 = 0.

It might be easier to think of that equation as 9 = b - 1. It seems to be clearer that you can isolate b by adding 1.

[gillshannon258]

THANK YOU !

[mybishthing]

thanks so much man!

you saved me

[beastbrian09]

i got lost early, cuz u didnt work out the x + 7y = 4

[georgewoodbury]

@beastbrian09

The goal is to isolate y.

Start by subtracting x from both sides. x + 7y = 4

-x -x

-------------

7y = -x + 4  (We usually write the term with x first so it is in y=mx+b form.)

Next we divide each term on both sides by 7 so we are left with y alone on the left side of the equation.

7y/7 = -x/7 + 4/7

You end up with y = -1/7 x + 4/7

Hope this helps.

[jadethefun]

wow! thanks a lot!!!

it helps me do my take home quiz!!

[courtnstar]

I've been given the following question:

P(4,0) L y = 1 - 2x

I've looked everywhere and I can't find a question like this on youtube.

I don't understand why it's "y = 1 - 2x" because it doesn't follow "2 = mx + c"

[courtnstar]

@courtnstar I meant it doesn't follow "y = mx + c"