Factorize: x⁴+x²+25.

Find the value of x³+y³-12xy+64,whenx+y=-4.

Multiply:

(i) x²+y²+z²-xy+xz+yzbyx+y-z

(ii) x²+4y²+z²+2xy+xz-2yzbyx-2y-z

(iii) x²+4y²+2xy+-3x+6y+9byx-2y+3

(iv) 9x²+25y²+15xy+12x-20y+16by3x-5y+4

Factorize: x²-1-2a–a².

If a + b + c = 0, then write the value of a³+b³+c³.