求下函数的最大最小值及达到最大(小)时的x的值的集合 y=3/2sin(2Pix+4Pi/3)

显示全部楼层 · 2008-11-27 21:21:41

y=3/2sin(2πx+4π/3)当sin(2πx+4π/3)=1,即2πx+4π/3=2kπ+π/2,x=k-5/12,k∈Z时,y max=3/2.这时x∈{x│x=k-5/12,k∈Z}.当sin(2πx+4π/3)=-1,即2πx+4π/3=2kπ-π/2,x=k-11/12,k∈Z时,y min=-3/2.这时x∈{x│x=k-11/12,k∈Z}.∴...

千问 · 2008-11-27 21:21:41

sin(2πx+4π/3)=1则2πx+4π/3=2kπ+π/22x+4/3=2k+1/2,x=k-5/12sin(2πx+4π/3)=-1则2πx+4π/3=2kπ-π/22x+4/3=2k-1/2,x=k-11/12所以y最大=3/2，此时x∈{k-5/12，k∈Z}y最小=-3/2，此时x∈{k-11/12，k∈Z}...