Question

The coefficient of the $x^2{y}^3{z}^2$ term in the expansion of $(x+y+2z{)}^7$, is

• A. $840$
• B. 420
• C. 210
• D. 180

Answer 1

Answer: (A)

Required coefficient is $\frac{4\cdot 7!}{2!\cdot 3!\cdot 2!}=\frac{4\cdot 7\cdot 6\cdot 5\cdot 4\cdot 3\cdot 2\cdot 1}{24}=4\times 210=840$