Writing an expression of the form $X^2 − A^2$ "Write the following expressions in the form $X^2 − A^2$ using the method of completing the square."
"1) $x^2 + 8x + 9$"
I don't understand how that can be, but I did try to do it, with no obvious next steps.
My solution:-
$x^2 + 8x + 16 -16 + 9$
$(x + 4)^2 - 7$
I completed the square, but how can I put that in the form $X^2 - A^2$?

'$x$' isn't the same as '$X$', so $(x+4)^2 − 7$ can be written in the form $X^2 - A^2$. Particularly, $(x+4)$ can be considered as $X$, and $\sqrt{7}$ can be considered as $A$. So, the expression in the designated form would be $(x+4)^2 - (\sqrt{7})^2$.
