13.设x=$\frac{1}{3-5\sqrt{2}}$,y=3+$\sqrt{2}$π,集合M={m|m=a+$\sqrt{2}$b,a∈Q,b∈Q},那么x,y与集合M的关系是( )
A. | x∈M,y∈M | B. | x∈M,y∉M | C. | x∉M,y∈M | D. | x∉M,y∉M |
9.下列函数中,满足关系f(x+y)=f(x)+f(y)的是( )
0 249907 249915 249921 249925 249931 249933 249937 249943 249945 249951 249957 249961 249963 249967 249973 249975 249981 249985 249987 249991 249993 249997 249999 250001 250002 250003 250005 250006 250007 250009 250011 250015 250017 250021 250023 250027 250033 250035 250041 250045 250047 250051 250057 250063 250065 250071 250075 250077 250083 250087 250093 250101 266669
A. | f(x)=x2 | B. | f(x)=x+$\frac{1}{4}$ | C. | f(x)=2x | D. | f(x)=$\frac{1}{x}$ |