1)(x+2)(x-2)-(x+2)^22)(a-2)(a-6)-(a-4)^23) 1 1 ____ - ____ 3x+y 3x-y4) m(m+2) m+2...

(x+2)(x-2)-(x+2)^2=x^2-4-x^2-4x-4=-4x-8

(a-2)(a-6)-(a-4)^2=a^2-8a+12-a^2+8a-16=-4

$\frac{1}{3x+y} - \frac{1}{3x-y} = \frac{3x-y-3x-y}{9x^2-y^2} = \frac{-2y}{9x^2-y^2}$

$\frac{m(m+2)}{m^3-8}- \frac{m+2}{m^2-2m+4} = \frac{m(m+2)}{m^3-8}- \frac{(m+2)(m+2)}{m+2)(m^2-2m+4)} = \\\ = \frac{m^2+2m-m^2-4m-m^2}{m^3-8}= \frac{-m(2-m)}{(m-2)(m^2+2m+4)}= \\\ = \frac{m}{m^2+2m+4}$

$\frac{x}{5} - \frac{x}{2} =6 2x-5x=60 \\\ -3x=60 \\\ x=-20$

$y=ax^2 \\\ -8=2^2a \\\ -8=4a \\\ a=-2$

$y=ax^4 \\\ 16=(-2)^4a \\\ 16=16a \\\ a=1$