Question 24: Simplify the expression \(B=\left(3 x^{2}-2 x+1\right) \cdot\left(3 x^{2}+2 x+1\right)-\left (3 x^{2}+1\right)^{2} \)

We have

\(\begin{aligned} &B=\left(3 x^{2}-2 x+1\right) \cdot\left(3 x^{2}+2 x+1\right)-\left(3 x^{2}+1\right)^{2} \\ &=\left(3 x^{2}+1\right)^{2}-(2 x)^{2}-\left(3 x^{2}+1\right)^{2} \\ &=-(2 x)^{2}=-4 x^{2} . \end{aligned}\)