Question:
Factorise:
x2 + 15x + 56
Solution:
The given expression is $x^{2}+15 x+56$.
Find two numbers that follow the conditions given below:
Sum $=15$
Product $=56$
Clearly, the numbers are 8 and 7 .
$x^{2}+15 x+56=x^{2}+8 x+7 x+56$
$=x(x+8)+7(x+8)$
$=(x+8)(x+7)$