It is true because
when you separate 2y^2 +9y -18, you are supposed to get the factors
(2y-3)(y+6), when you multiply this it gives you the first equation, we know
this because when we multiply the first term it gives us exactly 2y^2 and if we
multiply the last ones it gives you -18, now here is the tricky part, when we
multiply the middle part we get 12y and -3y, when we add these up we get 9y,
now is that the same middle as in the equation? Yes… then our factors are correct
making this true