Question

The number of terms in the expansion of $(x+y+z{)}^{10}$ is

• A. $88$
• B. $55$
• C. $66$
• D. $77$

Answer 1

The correct option is C $66$

Given expansion is $(x+y+z{)}^{10}$
So, the number of terms
$={}^{n+r-1}{C}_{r-1}={}^{10+3-1}{C}_{3-1}={}^{12}{C}_2=\frac{12\times 11}{2}=66$