>>80
2xx + 8x = 2x(x+4)
= 2(x+2 - 2)(x+2 + 2)
= 2(x+2)(x+2) - 8

2xx - 6x + 5 = 2x(x - 3) + 5
= 2(x - 3/2 + 3/2)(x - 3/2 - 3/2) + 5
= 2(x - 3/2)(x - 3/2) - 9/2 + 10/2
= 2(x - 3/2)(x - 3/2) + 1/2