Practice: Directional Derivative (2)

Calculate Dvf(x, y, z) D_{\vec{v}}f(x,~y,~z)~where f(x, y, z)=9x13z12+y1010 f(x,~y,~z)=9x^{\frac{1}{3}}z^{\frac{1}{2}}+\frac{y^{10}}{\sqrt{10}}~in the direction of v= <1, 0, 1>.\vec{v}=~<-1,~0,~1>.
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