You reflect a function with respect to the axis by changing its sign.
In fact, if you consider the two alternatives
and
you can see that you're choosing opposite outputs for the same inputs.
In other words, one graph will be made of points like , the other of points like
And the transformation
is exactly a reflection with respect to the axis.
Sometimes, fractions can be written in 'improper' form, meaning that the top number (numerator) is bigger than the bottom number (denominator). So anything multiplied by a fraction like this will give a bigger number.
For example:
5 × 2/1 = 10
10 x 10/1 = 100
X² - 64 = 0
(x - 8)(x + 8) = 0
x = - 8, 8
Your other solution is - 8