The value of (506)−(51)(406)+(52)(306)−(53)(206)+(54)(106) where (nr) denotes nCr is
2250000
50C6−5C140C6+5C230C5−5C320C6+5C410C6 =
coefficient of x6 in
[ 5C0(1+x)50−5C1(1+x)40+5C2(1+x)30−5C3(1+x)20+5C4(1+x)10−5C5(1+x)0]
coefficient x6 in [(1+x)^{10} - 1]^{5} \)
= coefficient of x6 in ({}^{10} C_1 x + {}^{10} C_2x^2 + ....)^5 = {}^5C_1 ({}^{10} C_{(b):} ({}^{10}C_1)^4 \) = 2250000