Question 513064
<pre>
p<sup>4</sup> - 10p<sup>2</sup> + 25 - t<sup>4</sup>

Factor the first three terms 

(p<sup>2</sup>-5)(p<sup>2</sup>-5) - t<sup>4</sup>

(p<sup>2</sup>-5)<sup>2</sup> - t<sup>4</sup>

Factor as the difference of squares:

[(p<sup>2</sup>-5) - t<sup>2</sup>][(p<sup>2</sup>-5) + t<sup>2</sup>]

Remove the inner parentheses 

[p<sup>2</sup> - 5 - t<sup>2</sup>][p<sup>2</sup> - 5 + t<sup>2</sup>]
 
Change the brackets to parentheses:

(p<sup>2</sup> - 5 - t<sup>2</sup>)(p<sup>2</sup> - 5 + t<sup>2</sup>)

It's customary to put the constant term last:

(p<sup>2</sup> - t<sup>2</sup> - 5)(p<sup>2</sup> + t<sup>2</sup> -5)

Edwin</pre>