Which expression is equivalent to 12x − 8x + 3 and why?

3 + 4x, because (12x − 8x) + 3 = 4x + 3 = 3 + 4x
7x, because 12x − 8x + 3 = 4x + 3 = 7x
12x − 5, because 12x − (8x − 3) = 12x − 5
x, because 12x − 8x + 3 = 12x − 11x = x

Exercise: counting committees 0.0/2.0 puntos (calificable) we start with a pool of n people. a chaired committee consists of k≥1 members, out of whom one member is designated as the chairperson. the expression k(nk) can be interpreted as the number of possible chaired committees with k members. this is because we have (nk) choices for the k members, and once the members are chosen, there are then k choices for the chairperson. thus, c=∑k=1nk(nk) is the total number of possible chaired committees of any size. find the value of c (as a function of n ) by thinking about a different way of forming a chaired committee: first choose the chairperson, then choose the other members of the committee. the answer is of the form c=(α+nβ)2γn+δ. what are the values of α , β , γ , and δ ?