Question

The number of terms, which are free from radical signs in the expansion of (y^1/5 + x^1/10)⁵⁵ is-

• A. 5
• B. 6
• C. 7
• D. None

Answer 1

Answer: (B)

6

Answer 2

T_r+1 = ⁵⁵C_r. $y^{\frac{55 - r}{5}}$.$x^{\frac{r}{10}}$= ⁵⁵C_r $y^{\frac{11 - r/10}{5}}$. $x^{\frac{r}{10}}$

\ r = 0, 10, 20, 30, 40, 50