a)
m^2-n^2=(m+n)(m-n)
b)
16 - z^2=(4+z)(4-z)
c)
9a^2 - 1/49=(3a+\frac{1}{7})(3a-\frac{1}{7})
d)
0,09c^2 - 100d^2=(0,3c+10d)(0,3c-10d)
e)
9s^4 - r^6=(3s^2+r^3)(3s^2-r^3)
f)
4a^2b^4 - c^6=(2ab^2+c^3)(2ab^2-c^3)
g)
0,16x^{16} - \frac{1}{81}=(0,4x^8+\frac{1}{9})(0,4x^8-\frac{1}{9})
h)
2a^6 - 3 b^2 c^{10}=(\sqrt2a^3+\sqrt3bc^5)(\sqrt2a^3-\sqrt3bc^5)
i)
\frac{x^4}{9y^2z^4}-\frac{z^6}{x^2}=(\frac{x^2}{3yz^2}+\frac{z^3}{x})(\frac{x^2}{3yz^2}-\frac{z^3}{x})