Question 340348
1.{{{x^4-81=(x^2-9)(x^2+9)=(x-3)(x+3)(x^2+9)=(x-3)(x+3)(x-3i)(x+3i)}}} where {{{i=sqrt(-1)}}}
2.{{{y^4-8y^2-48=(y^2-12)(y^2+4)=(y-2sqrt(3))(y+2sqrt(3))(y-2i)(y-2i)}}} where {{{i=sqrt(-1)}}}
3.{{{ 8a^3-b^3=(2a-b)(4a^2+2ab+b^2)}}}
4.{{{  25x^2+30x+9=(5x+3)^2}}}
5.{{{x^2+16 =(x+4i)(x-4i)}}} where {{{i=sqrt(-1)}}}