A: 2,3
B:-2,3
C:-2,-3
D:2,-3
乘积5×6×7×⋯×20等于( )
— Tom, touch your eye.
— This is my eye.
已知曲线C的参数方程为x=t2-4t2+4y=8tt2+4(t为参数).求曲线C的普通方程;