If r=130 r2 (30Cr )230Cr-1= 229, then is equal to .
Answer
465
Solution
30Cr30Cr-1= 31-rr term =(31-r) r 30Cr=30(31-r) 29Cr-1 (as r nCr=n n-1Cr-1)
j=r-1: S=30 j=029(30-j) 29Cj=30 [30 229-29 228 ]
=30 31 228=465 229
=465
Answer: 465
If r=130 r2 (30Cr )230Cr-1= 229, then is equal to .
465
30Cr30Cr-1= 31-rr term =(31-r) r 30Cr=30(31-r) 29Cr-1 (as r nCr=n n-1Cr-1)
j=r-1: S=30 j=029(30-j) 29Cj=30 [30 229-29 228 ]
=30 31 228=465 229
=465
Answer: 465
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