y=f(x+2)是偶函数,所以f(-x+2)=f(x+2)
所以f(5/2)=f(1/2+2)=f(-1/2+2) = f(3/2)
f(7/2)=f(3/2 +2)=f(-3/2 +2) =f(1/2)
而由单增性有 f(1/2)