How do use the binomial theorem to calculate 10C7?
1 Answer
Aug 15, 2017
Explanation:
"using the definition of the "color(blue)"binomial coefficient"using the definition of the binomial coefficient
color(white)(x)^nC_r=(n!)/(r!(n-r)!)xnCr=n!r!(n−r)!
"where "n! =n(n-1)(n-2)......xx1
rArr^(10)C_7=(10!)/(7!xx3!)
color(white)(xxxxxx)=(10xx9xx8xxcolor(red)cancel(7xx6xx5xx4xx3xx2))/(color(red)cancel(7xx6xx5xx4xx3xx2)xx3xx2
color(white)(xxxxxx)=(10xx9xx8)/(3xx2)=120