10.把x换为1/x,得
f(1/x)=(1+1/x)/(1-1/x)=(x+1)/(x-1)选 看不见,不选AB
13.把 x换为x+1,得
f(x+1)=(x+1)³+4(x+1)²+11(x+1)+7
=x³+3x²+3x+1+4x²+8x+4+11x+11+7
=x³+7x²+22x+23
选A
10.把x换为1/x,得
f(1/x)=(1+1/x)/(1-1/x)=(x+1)/(x-1)选 看不见,不选AB
13.把 x换为x+1,得
f(x+1)=(x+1)³+4(x+1)²+11(x+1)+7
=x³+3x²+3x+1+4x²+8x+4+11x+11+7
=x³+7x²+22x+23
选A