BITSAT2016MathematicsBinomial TheoremActual
If the third term in the expansion of [ x + x ^ ₁₀ x ]⁵ is 10⁶, then x may be
Options
- A1
- B10
- C10
- D10^ -2 / 5
Correct answer
C. 10
Step-by-step solution
Put ₁₀ x=y, the given expression becomes (x+x^ y )⁵ T ₃= ⁵ C ₂ x ³ ( x ^ y )²=10 x ^ 3+2 y =10⁶ (given) (3+2 y ) ₁₀ x =5 ₁₀ 10=5 (3+2 y ) y =5 y =1,- 5 2 ₁₀ x =1 or ₁₀ x =- 5 2 x =10 or x =(10)^ -5 / 2