A 2.26 kg object is subjected to three forces that give it an acceleration

Question

a= −(8m/s^2)i + (6m/s^2)j. If two of the three forces are F1 = (36.2 N)i + (18N)j and F2 = −(12N)i + (8N)j,find the third force.

Answer 1

f = m a

net force = -[(8m/s^2)/(2.26 kg)]i +
[(6m/s^2)/(2.26 kg)]j

subtract F1 and F2 from the net force to find F3

Answer 2

F = ma
so
F= -8*2.26 i + 6*2.26 j
so
-8*2.26 = 36.2 -12 + F3x
and
6*2.26 = 18 + 8 + F3y

and then
F3 = F3x i + F3y j

Answer 3

F = m * a not m / a

Answer 4

or a/m :)