曲面x^2+2y^2+3z^2=21在点(1,-2,2)处的法线方程是().A. (x-1)/(1)=(y+2)/(-4)=(z-2)/(6)B. (x+1)/(1)=(y-2)/(-4)=(z+2)/(6)C. (x-1)/(-1)=(y+2)/(-4)=(z-2)/(-6)D. (x+1)/(-1)=(y-2)/(4)=(z+2)/(-6)

曲面$x^{2}+2y^{2}+3z^{2}=21$在点$(1,-2,2)$处的法线方程是().

A. $\frac{x-1}{1}=\frac{y+2}{-4}=\frac{z-2}{6}$

B. $\frac{x+1}{1}=\frac{y-2}{-4}=\frac{z+2}{6}$

C. $\frac{x-1}{-1}=\frac{y+2}{-4}=\frac{z-2}{-6}$

D. $\frac{x+1}{-1}=\frac{y-2}{4}=\frac{z+2}{-6}$