Comparing x2+5x+6 with x2+(a+b)x+ab
We have, ab=6,a+b=5 and x=x.
If ab=6, it means a and b are factors of 6.
Let us try with a=2 and b=3. These values satisfy ab=6 and a+b=5.
Therefore the pair of values a=2andb = 3$ is the right choice.
Using, x2+(a+b)x+ab=(x+a)(x+b)
x2+5x+6=x2+(2+3)x+(2×3)
=(x+2)(x+3)
∴(x+2) and (x+3) are the factors of x2+5x+6.