(-5)^2+(-4)^2+(-3)^2+............+11th term
pls.
sum of 11th term
2007-06-04 7:17 pm
回答 (5)
2007-06-05 7:46 pm
✔ 最佳答案
(-5)^2+(-4)^2+(-3)^2+............+11th term= 25+16+9+4+1+0+1+4+9+16+25
= 2*(25+16+9+4+1) = 110
you may also use 1^2 + 2^2 + ... + n^2 = n(n+1)(2n+1)/6,
but I don't think it would be useful becuase n is very small, it can be easily calculated by addition.
參考: me
2010-07-17 5:22 am
2007-06-07 1:29 am
1^2 + 2^2 + ... + n^2 = n(n+1)(2n+1)/6 是一條公式
(-5)^2+(-4)^2+(-3)^2+............+11th term
(1^2+2^2+3^2+4^2+5^2)x2
=(5x6x11/6)x2
=110
(-5)^2+(-4)^2+(-3)^2+............+11th term
(1^2+2^2+3^2+4^2+5^2)x2
=(5x6x11/6)x2
=110
參考: me
2007-06-06 1:57 am
(-5)^2+(-4)^2+(-3)^2+(-2)^2+(-1)^2+...+11th term
=(-5)^2+(-4)^2+(-3)^2+(-2)^2+(-1)^2+(0)^2+(1)^2+(2)^2+(3)^2+(4)^2+(5)^2
=25+16+9+4+1+0+1+4+9+16+25
=110
=(-5)^2+(-4)^2+(-3)^2+(-2)^2+(-1)^2+(0)^2+(1)^2+(2)^2+(3)^2+(4)^2+(5)^2
=25+16+9+4+1+0+1+4+9+16+25
=110
參考: Myself!
2007-06-05 8:04 pm
Because
(-5)^2 = 5^2
(-4)^2 = 4^2
(-3)^2 = 3^2
... and so on.
Also,by Pyth.th, 4^2 + 3^2 = 5^2
Therefore,
(-5)^2+(-4)^2+(-3)^2+............+11th term
=(5^2 + 5^2 + 2^2 + 1^2) x2
=(25+25+2+1)x2
=53x2
=106
2007-06-05 12:05:43 補充：
Sorry, 更正=(25 25 4 1)x2=55x2=110
(-5)^2 = 5^2
(-4)^2 = 4^2
(-3)^2 = 3^2
... and so on.
Also,by Pyth.th, 4^2 + 3^2 = 5^2
Therefore,
(-5)^2+(-4)^2+(-3)^2+............+11th term
=(5^2 + 5^2 + 2^2 + 1^2) x2
=(25+25+2+1)x2
=53x2
=106
2007-06-05 12:05:43 補充：
Sorry, 更正=(25 25 4 1)x2=55x2=110
參考: 自己
收錄日期: 2021-04-12 19:52:10
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