Question

Multiply:​

$\left(ii\right)$ $3ab-4b\text{by}3ab$

Answer 1

Find the product of $3ab-4b$ and $3ab$
To find: $(3ab-4b)\times 3ab$

The multiplication of monomials can be performed by multiplication of their coeffficients and literals.

$\therefore (3ab-4b)\times 3ab$
$=3ab\times 3ab-4b\times 3ab$
$=(3\times 3)\times (ab\times ab)-(3\times 4)\times (b\times ab)$
$=9a^{1+1}{b}^{1+1}-12a{b}^{1+1}$
$=9a^2{b}^2-12a{b}^2$

Hence, the product of $3ab-4b$ and $3ab$ is $9a^2{b}^2-12a{b}^2$.