如题所述
M={ x| x=a+√2b , a,b∈Z}
0= 0+0(√2) , a=b=0
=>0∈M
-1= -1+0(√2) ,a=-1, b=0
=>-1∈M
3√2-1 = -1 + 3√2 , a=-1, b=3
=>3√2-1∈M
2/(3-2√2) =2(3+2√2)=6+4√2 , a=6,b=4
=>2/(3-2√2)∈M
√8=0+2√2 , a=0,b=2
=>√8∈M
1/(1-√2) = 1+√2 , a=1, b=1
=>1/(1-√2)∈M
ans :A