If p is a real number and the middle term in the expansion (p/2 + 2)8 is 1120, then find the value of p.
Given: (p/2 + 2)8
Now, here index is n = 8,
Since there is only one middle term, viz., (8/2 + 1)th i.e., the fifth term
T5 = T4+1
= 8C4(p/2)8-4. 24
Now,
1120 = 8C4p4
1120 = 8x7x6x5x4!/4!x4x3x2x1 . p4
1120 = 7x2x5xp4
Thus, p4 = 1120/70
p4= 16
p2 = 4
Thus, p = ±2