llllllllllllllllllllllllllllllllllllllllllllllllll (18 11:40:56)已知函数f（X）=ax+b,若f(0)=1,且f(x+1)=f(x+1)=f(x)+3,求f(x).
问题描述：
llllllllllllllllllllllllllllllllllllllllllllllllll (18 11:40:56)
已知函数f（X）=ax+b,若f(0)=1,且f(x+1)=f(x+1)=f(x)+3,求f(x).
答
是3x+1吗？
答
将f（0）带进去得到b=1 ,则f（x+1）=a（x+1）+1 ,f（x）+3=ax+4
又f(x+1)=f(x)+3,即a（x+1）+1 =ax+4 化简得到a=3
所以f(x）=3x+1