Ineed , 30+ points and brainliest if you

He couldn't have factored it correctly because 1x x 1x is not 2x its 1x.

1.  No, Bo made an error on Line 3.  When he pulled out x from x² - 8xy, the result should have been x(x - 8y).  Instead, Bo wrote x(x - 8).  It should go like this:

Line 1:  x² - 10xy + 16y²
Line 2: x² - 8xy - 2xy + 16y²
Line 3: x(x - 8y) - 2y(x - 8y)

After this, we can pull out the factor (x - 8y):

Line 4: (x - 2y)(x - 8y)

2.  I'm not 100% positive, but I think you would have to look at a and c in the equation y = ax² + bxy + cy².  If they are prime numbers, I believe that the equation would be prime.