A
I − A
I
3A
(I+A)3-7A =I3+A3+3I2A+3A2I-7A
=I+A3+3A+3A2-7A
=I+A2.A+3A+3A-7A [A2=A]
=I+A2-A
=I+A-A
=I
\(\therefore\) (I+A)3-7A=I
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?