Question:
Factorise:
7x2 − 19x − 6
Solution:
The given expression is $7 x^{2}-19 x-6$.
Find two numbers that follow the conditions given below:
Sum $=-19$
Product $=7 \times-6=-42$
Clearly, the numbers are $-21$ and 2 .
$7 x^{2}-19 x-6=7 x^{2}-21 x+2 x-6$
$=7 x(x-3)+2(x-3)$
$=(7 x+2)(x-3)$