will we destroy x - sixteen down? we are in a position to if we cope with it via fact the version of two squares: x - sixteen => (sqrt(x) - 4) * (sqrt(x) + 4) (4 - sqrt(x)) / ((sqrt(x) - 4) * (sqrt(x) + 4)) => -a million / (sqrt(x) + 4) x is going to sixteen -a million / (sqrt(sixteen) + 4) => -a million / (+/- 4 + 4) => -a million / (-4 + 4) or -a million / (4 + 4) -a million / (-4 + 4) does not exist, so: -a million / 8 is the decrease