(i) We have: A'=\(\begin{bmatrix}1&-1&5\\-1&2&1\\5&1&3\end{bmatrix}\)=A so A'=A
(i) We have: A'=\(\begin{bmatrix}0&-1&1\\1&0&-1\\-1&1&0\end{bmatrix}\)=-\(\begin{bmatrix}0&1&-1\\-1&0&1\\1&-1&0\end{bmatrix}\)=-A
so A'=A Hence, A is a skew-symmetric matrix.
Let \[ f(x)=\int \frac{7x^{10}+9x^8}{(1+x^2+2x^9)^2}\,dx \] and $f(1)=\frac14$. Given that 
If vector \( \mathbf{a} = 3 \hat{i} + 2 \hat{j} - \hat{k} \) \text{ and } \( \mathbf{b} = \hat{i} - \hat{j} + \hat{k} \), then which of the following is correct?