Page 164 - Fixtures

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( ) nr = −12

( ) n(n − 1) r2 = 60

2

r

n(n − 1) × 144 = 60
2 n2
72(n − 1) = 60n

72n − 72 = 60n

12n = 72

.r = −2 n = 6 , n=6

.r = −12 = −2

n

()

C(n, 0) −C(n,1) +C(n,2) −C(n, 3) + + (−1)nC(n,n)
=0

y = −1 x = 1 (x + y)n

. ∑ ∑n n
0 = (1 + (−1))n = C(n,k)1n−k (−1)k = (−1)kC(n,k)
k=0 k=0

. n C (n, k )2k ()

∑
k=0