Factor out 2






Look at the last term 36.

Think of two positive integers that

1.  Have PRODUCT 36

and  (look at the sign before 36)

2.  Have SUM  (If that sign had been -, it would be DIFFERENCE)

3.  of 12 (the coefficient of h)

4.  That's 6 and 6, because 6∙6=36 and 6+6=12

4. So we write this



Since the sign of 36 is +, we think 3 S's: "SUM, SAME SIGN",
so we put the SAME SIGN, the sign of 12 between the terms 
inside the parentheses:



One more step.  Since the (h+6) is repeated, we write
it once with a square, or exponent of 2:

2(h + 6)2

Edwin