若f(x+2)=2x+3,则f(x)等于( ) A.2x+1 B.2x-1 C.2x-3 D.2x+7
问题描述:
若f(x+2)=2x+3,则f(x)等于( )
A. 2x+1
B. 2x-1
C. 2x-3
D. 2x+7
答
令x+2=t,则x=t-2,
则f(t)=2(t-2)+3
=2t-1.
故选B.