general form is ax^2+bx+c, and to get there we need to factor using FOIL (First Outside Inside Last)
(2x-1)(x+5)
F (2x × x)= 2x^2
O (2x × 5) 10x
I (-1 × x) -x
L (-1 × 5) -5
now add them together
2x^2+10x-x-5
2×^2+9x-5
and because the equation is in the form
ax^2+bx+c b is equal to 9
