Answer:
<2, -4, 0>
Step-by-step explanation:
Given vectors,
u = <2, 1, -1>
⇒ u = 2i + j - k
v = <2, 1, 1>
⇒ v = 2i + j + k
∵ The cross product of u and v is a orthogonal or perpendicular vector to both vectors u and v,
![\because u* v=\begin{vmatrix}i & j &k \\ 2 & 1 & -1\\ 2 & 1 & 1\end{vmatrix}](https://img.qammunity.org/2020/formulas/physics/college/96k81pmt9y2kz90ybgrxxqs6v0baeddukb.png)
![=i(1+1)-j(2+2)+k(2-2)](https://img.qammunity.org/2020/formulas/physics/college/48oxhl8hnreatlsop0gjq5jzkxqzdt4hd8.png)
= 2i - 4j + 0k
Hence, the vector which is perpendicular to both u and v is <2, -4, 0>