[tex]6 x^{2} +24x+21[/tex]
Multiply 6 and 21 and you get 126. You will need to find two factors of 126 which will add up to 24 (the middle number of the equation). After guess and check, the two numbers are 14 and 9. Instead of 24x, replace it with 14x and 9x.
[tex]6 x^{2} +14x+9x+21[/tex]
Factorise each pair separately,
[tex]2x(3x+7) + 3(3x+7)[/tex]
[tex](3x+7)(2x+3)[/tex]
Hope this helped!
