Verified answer

(x+y)^2-4x-4y+4=(x+y)^2-4(x+y)+4=[(x+y)-2]^2

and

y^4+6y^2+25

=[y^4+10y^2+25]-4y^2

=[y^2+5]^2-4y^2

=[y^2+5-2y][y^2+5+2y]

=[y^2-2y+5][y^2+2y+5]

y^4+6y^2+25

this is a trick question:

answer: (y^2)^2 + 2(3y^2) +25

this is a curious question:

(x+y)^2-4x-4y+4

answer: (x+y)^2 +4(1-x-y)

for number one

first try factoring 4x-4y+4 (factoring a trinomial)

then you should be left with a difference of sqaures

hope that helps..

(x+y)^2 - 4(x+y) + 4 = [(x+y)-2]^2

Sorry; can't help with the other one