Answer:
![u= -(1)/(√(6)) ,-(1)/(√(6)) ,-(2)/(√(6))](https://img.qammunity.org/2022/formulas/mathematics/college/4jkzb92fqb88nu20m7sjn8nfubt252z844.png)
Explanation:
From the question we are told that
Temperature is given
\
A fly is at (1,2,1)
Generally the direction of fly is given by
![\triangleT(x,y,z) =(1,z,y)\\](https://img.qammunity.org/2022/formulas/mathematics/college/4hd5b8u2v5xgvc6ge0goy0eip1giiqho6v.png)
![v= \triangleT(1,2,1)\\v=(1,1,2)](https://img.qammunity.org/2022/formulas/mathematics/college/rixk5ntn4ljs7wkhlsnrz7kndc44prdvb8.png)
Mathematically solving for the vector direction
![|v|=√(1^2+1^2+2^2)](https://img.qammunity.org/2022/formulas/mathematics/college/cawmmxsqa8x60meqfio4ctxtpo4sd008x1.png)
![|v|=√(6)](https://img.qammunity.org/2022/formulas/mathematics/college/yv87chperzkm06zra77pe11mra5rlb77pu.png)
![u=- (v)/(|v|)](https://img.qammunity.org/2022/formulas/mathematics/college/92dv1c37wfaj5i5yyy0abattz239qvwlim.png)
![u= -(1)/(√(6)) ,-(1)/(√(6)) ,-(2)/(√(6))](https://img.qammunity.org/2022/formulas/mathematics/college/4jkzb92fqb88nu20m7sjn8nfubt252z844.png)
Therefore this the direction which should be taken to cool down soonest