Question

Factorise x²+9x+18

Answer 1

Solution- The given expression is $x^{2}+9 x+18$.
We try to split 9 into two parts whose sum is 9 and product 18 .
Clearly, $6+3=9$ and $6 \times 3=18$.
$
\begin{aligned}
\therefore \quad x^{2}+9 x+18 &=x^{2}+6 x+3 x+18 \\
&=x(x+6)+3(x+6) \\
&=(x+6)(x+3) .
\end{aligned}
$
Hence, $x^{2}+9 x+18=(x \div 6)(x+3)$