Question

$\text{Factorise the expression}15a^{3}b+35a{b}^3.$ (2 marks)

Answer 1

$\text{Given, the expression is}15a^{3}b$ + $35a{b}^3.$

On writing each term as the product of irreducible factors, we get,
$15a^{3}b$ = $3\times 5\times a\times a\times a\times b$
$35a{b}^3$ = $5\times 7\times a\times b\times b\times b$
(0.5 marks)
By taking out the common factors, we get,
$15a^{3}b+35a{b}^3=5ab(3a^2+7b^2)$ (1.5 marks)