Explanation:
3m(2m - 1) + 6m(4m - 1) = 6m² - 3m + 24m² - 6m =
= 30m² - 9m = 3m(10m - 3)
for m = -⅓ we get
30×(-⅓)² - 9×(-⅓) = 30×1/9 - -9/3 = 10/3 + 9/3 =
= 19/3 = 6 ⅓ = 6.3333333...
as a controls
3×(-⅓)×(10×(-⅓) - 3) = -1×(-10/3 - 3) = 10/3 + 3 =
= 10/3 + 3×3/3 = 10/3 + 9/3 =
= 19/3
correct.
3×(-⅓)×(2×(-⅓) - 1) + 6×(-⅓)×(4×(-⅓) - 1) =
= -1×(-⅔ - 1) + -2×(-4/3 - 1) =
= ⅔ + 1 + 8/3 + 2 = ⅔ + 3/3 + 8/3 + 6/3 = 19/3
correct.