√2x^2-4x=4√2
√2x^2-4x-4√2=0
x^2-4x/√2-4=0
x^2-2√2x-4=0
x^2-2√2x+2-2-4=0
(x-√2)^2-6=0
(x-√2-√6)(x-√2+√6)=0
x=√2+√6或x=√2-√6
4y2-(根号2+8)y+2根号2=0
(4y-根号2)(y-2)=0
所以
y=√2/4或y=2