Question 912345
You just need to try all the combinations (until or unless you know another way).


{{{7p^2+18p-9=0}}}


Try these:


(7p+u)(p+v) and you must have 7pv+up=(7v+u)p=18p and u*v=9.
Pick your possible combinations u and v for the product 9.
You have 1 and 9
OR
you have 3 and 3.
You must expect one of the numbers positive and one of them negative.


{{{(7p+- 1)(p+- 9)}}}, check this.

OR 

{{{(7p+- 3)(p+- 3)}}}, check this.

OR

{{{(7p+- 9)(p+- 1)}}}, check this.


Which combination (including signs) works?


(Note that the rendering is working but is difficult to read).




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ANSWER:   (7p-3)(p+3)