✔ 最佳答案
start by multiplying out:
2(9m^2 + 12m + 4) + 21m + 14 = -6
18m^2 + 24m + 8 + 21m + 14 = -6
then collect terms:
18m^2 + 45m + 28 = 0
then solve the quadratic using the quadratic theorem,
(-b +/- sqrt(b^2 - 4ac))/2a, where the quadratic is of the form am^2 + bm + c , which yeilds the answers:
m = -4/3 & -7/6