将y=2cos(x3+π6)的图象按向量a=(−π4,−2)平移,则平移后所得图象的解析式为()
A.y=2cos(x3+π4)−2
B.y=2cos(x3−π4)+2
C.y=2cos(x3−π12)−2
D.y=2cos(x3+π12)+2