How do you factor #-63x^2 - 19x + 30#?
I use the new AC Method to factor trinomials (Google, Yahoo Search).
Convert y to
p' and q' have different signs (Rule of Signs). Compose factor pairs of (a.c = -1890) and find the pair whose sum is b.
Use a calculator and start from the middle:...(-30, 63)(-35, 54). This sum is (54 - 35 = 19 = b). Then, p' = -35 and q' = 54.
Back to y,
Factored form: y = -[(x - 5/9)(x + 6/7)] = -[(9x - 5)(7x + 6)]
Check by developing:
NOTE . The new AC Method is fast, systematic, no guessing, no factoring by grouping, and no solving binomials.