[Mt10]

1)))


n
∑ (2k-1) = 60 ise n ?
k=3




2)))

9
∑ (3n-x) = 0 ise x ?
n=-3

[duygu95]

C-1)

n-2

∑

k=3-2

(2(k+2)-1)

n-2

∑

k=1

(2k+3)

n-2

∑

k=1

2k+

n-2

∑

k=1

3

2

n-2

∑

k=1

k+3(n-2)

=2*(n-2).(n-1)/2+3(n-2)=60

(n-2).(n-1)+3(n-2)=60

(n-2)(n-1+3)=60
n=8 bulunur.

[duygu95]

C-2)

9+4

∑

n=-3+4

(3(n-4)-x)=0

13

∑

n=1

(3n-12-x)=0

3

13

∑

n=1

n-(12.13+x.13)=0

3.(13.14)/2-12.13-13x=0

x=9 bulunur.

[Mt10]

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