Question: 2015 Winter Final - 4
What is the coefficient of $x^{4}y^{11}$ in the expansion of $(2x - 7y)^{15}$?
(a)
$- {15 \choose 11} \cdot 2^{11} \cdot 7^4$
(b)
${15 \choose 11} \cdot 2^{11} \cdot 7^4$
(c)
$- {15 \choose 11} \cdot 2^4 \cdot 7^{11}$
(d)
${15 \choose 11} \cdot 2^4 \cdot 7^{11}$