How do you factor #y= -12r^2+5r+3# ?
to factor this trinomial
compare to general form:
first multiply ac in this case
now consider the factors of - 36 which also add together to give b =5 in this question .
the pairs of factors of - 36 are ( - 2 , 18 ) reject as sum ≠ 5
( - 3 , 12 ) reject as sum ≠ 5
( - 4 , 9 ) accept as sum = 5
now rewrite the function as
(Note 5r has been replaced by
factor the expression in pairs to give: