## anonymous 5 years ago Shortanswer question http://img151.imageshack.us/img151/6880/andysnap013.png

1. anonymous

Two lines will be parallel if they have the same gradient. Lines in the form$y=mx+b$are gradient-intercept form. If you rearrange your equations into that form, you can compare the gradients. To make the other line parallel, choose 'a' that will give you a gradient equal to the other.

2. anonymous

how do we re arrange? so is 5 from (5x) the gradient for the first one and a from (ax) the gradient of the other?

3. anonymous

$5x-y+10=0 \rightarrow y=5x+10$after adding 10 to both sides.

4. anonymous

The first line has gradient 5.

5. anonymous

$ax+4y-3=0 \rightarrow 4y=3-ax \rightarrow y = \frac{3-ax}{4}=-\frac{a}{4}x+\frac{3}{4}$

6. anonymous

You need a such that$-\frac{a}{4}=5$

7. anonymous

So a is -20.

8. anonymous

how did that become -a/4 x + 3/4 ?

9. anonymous

$y=\frac{3-ax}{4}=\frac{3}{4}-\frac{ax}{4}=-\frac{ax}{4}+\frac{3}{4}=-\frac{a}{4}x+\frac{3}{4}$

10. anonymous

oh okay makes sense :))) I'm just not so good at re arranging.

11. anonymous

practice practice practice so you don't get ruined in tests for nothing

12. anonymous

Very true :D

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