got 2 series. 1. 1^{2} - 2^{2} + 3^{2} - 4^{2} + ................. 99^{2} - 100^{2} (ok those are just squares) 2. 1.1! + 2.2! + ....... 50.50! need to find sum...
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Originally Posted by adhyeta got 2 series. 1. 1^{2} - 2^{2} + 3^{2} - 4^{2} + ................. 99^{2} - 100^{2} (ok those are just squares) need to find sum... finding the difference in pairs now giving 50 terms. Use sum of an arithmetic sequence where n = number of terms = 50 a = the first term = -3 and d = the common difference between terms = -4
Hello, adhyeta! Are you familiar with these summation formulas? . . . . . . Hence: . . .
Originally Posted by pickslides finding the difference in pairs now giving 50 terms. Use sum of an arithmetic sequence where n = number of terms = 50 a = the first term = -3 and d = the common difference between terms = -4 thats not coming out to be correct...its -5050. refer to soroban's solution.
Originally Posted by adhyeta thats not coming out to be correct...its -5050. refer to soroban's solution. Worked for me!
Last edited by pickslides; April 30th 2009 at 02:16 PM. Reason: Typo
Originally Posted by adhyeta got 2 series. 1. 1^{2} - 2^{2} + 3^{2} - 4^{2} + ................. 99^{2} - 100^{2} (ok those are just squares) 2. 1.1! + 2.2! + ....... 50.50! need to find sum... Here's the second one. Let so here so the answer .
Originally Posted by pickslides Worked for me! hey! so sorry. i think i went wrong with the calc.(-calculation-)
Originally Posted by danny arrigo Here's the second one. Let so here so the answer . hey! can we similarily prove the sum ???
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