## anonymous 3 years ago Divide: 5x^2-20x/4x-9 divide by x-4/4x-9

1. saifoo.khan

$\frac{5x^2-20x}{4x-9} \div \frac{ x-4}{4x-9 }$Change the divide sign: $\frac{5x^2-20x}{4x-9} \times \frac{ 4x-9}{x-4 }$

2. anonymous

Ok I get that part, then what?

3. anonymous

factor a 5x out of the top and you get 5x(x-4)

4. saifoo.khan

$\frac{5x^2-20x}{\cancel{4x-9}} \times \frac{ \cancel{4x-9}}{x-4 }$

5. anonymous

Do you see something in the top and bottom that can cancel out before you do any factoring?

6. anonymous

@saifoo.khan just illustrated my point

7. anonymous

I was going to say 4x-9

8. anonymous

Change sign, cancel out, what is the next step

9. saifoo.khan

|dw:1350791060484:dw|

10. anonymous

factor out a common multiple would be the next step illustrated above

11. anonymous

Ohhh I get it!

12. anonymous

We got lucky with this problem and you can see another canceling out possibility

13. anonymous

yes