## cutie.patootie Group Title More help? Type the equation of the given line in standard form. The line with m = 4 and intersecting 2x -4y = 8 at x = 6. Thanks! 2 years ago 2 years ago

1. agentx5

Step #1: convert "2x -4y = 8" to y=mx+b Step #2...

2. cutie.patootie

So that would make it -4y=2x+8?

3. cutie.patootie

Or do I have to put the m in there to and make it -4y=8x+8?

4. jazy

you want y not -4y so you should simplify

5. agentx5

Move the 2x over to the other side (with subtraction), divide both sides by -4. Can you write this second step @cutie.patootie ? :-) You'll end up getting a y=mx+b form line that allows to to draw this: |dw:1343071328047:dw|

6. cutie.patootie

-4y=2x+8 turns into.. -4y-2x=8 divide by -4 gives you.. y+(1/2)x=2 Right?

7. agentx5

No... unless you wrote it incorrect at the start. -4y + 2x = 8? Move the x's over -4y = -2x + 8 Divide by -4 y = 0.5 x - 2 (see graph above)

8. cutie.patootie

Oh well I had it right, but then I moved the x to the wrong side. But I see where I made my mistake now.

9. agentx5

then it tells you there is some other line with: y = 4x + b , because it says "m = 4" An "intersection of two lines" means when they are equal to each other. If you've solved both for the dependent varible (y) that means you can set the y's equal to each other: $$y_1 = y_2$$ we know: $$y_1 = \frac{1}{2}x - 2$$ $$y_2 = 4x + b_2$$ So... $$y_1 = y_2$$ $$\frac{1}{2}x - 2 = 4x + b_2$$ Make sense? The final steps are substitute in "x=6", solve for $$b_2$$, and rewrite $$y_2$$

10. cutie.patootie

Okay, so you get... (1/2)(6) - 2 = 4(6) +b2 3-2=24+b2 1=24+b2 b2= -23?

11. agentx5

You're correct! |dw:1343072679957:dw|

12. agentx5

When x = 6, they are both equal.

13. agentx5

Now don't forget to rewrite $$y_2=4x-23$$ in standard form :-) All good?

14. agentx5

Visual methods FTW!

15. cutie.patootie

Okay, I think I follow. So I write it y + 4x = -23?

16. cutie.patootie

And yes! Hahaha.