Question: Factorise:
x2 + 13x + 40
Solution:
The given expression is $x^{2}+13 x+40$.
Find two numbers that follow the conditions given below:
Sum $=13$
Product $=40$
Clearly, the numbers are 8 and 5 .
$x^{2}+13 x+40=x^{2}+8 x+5 x+40$
$=x(x+8)+5(x+8)$
$=(x+8)(x+5)$
