Question

Find the following product: (z² + 2) (z² − 3)

Answer 1

Here, we will use the identity​ \[\left( x + a \right)\left( x - b \right) = x^2 + \left( a - b \right)x - ab\].

\[\left( z^2 + 2 \right)\left( z^2 - 3 \right)\]

\[ = \left( z^2 \right)^2 + \left( 2 - 3 \right)\left( z^2 \right) - 2 \times 3\]

\[ = z^4 - z^2 - 6\]