Manipal MET2021MathematicsBinomial Theorem
The term independent of x in the expansion of (2 x^4- 1 x^2 )¹² is
Options
- A6920
- B7920
- C7900
- D3960
Correct answer
B. 7920
Step-by-step solution
The general term is aligned T_ r+1 & = ¹² C_r (2 x^4 )^r (- 1 x^2 )^ 12-r & = ¹² C_r(2)^r x^ 4 r (-1)^ 12-r (x)^ -2(12-r) aligned For term independent of x , we put aligned & 4 r-24+2 r=0 6 r=24 r=4 & aligned T₅ & = ¹² C₄(2)^4(-1)¹²⁻⁴ & = 12 11 10 9 4 3 2 1 (2)^4=7920 aligned aligned