Find the sum of : (a) 10 consecutive cubes starting from 1 , (b) 25 cubes starting from 1
Answers
Answered by
34
Solution :
We know that ,
Sum of n consecutive cubes
= [n(n+1)/2]²
1 ) Sum of 10 consecutive cubes
= [10(10+1)/2]²
= [5×6]²
= 30²
= 900
2 ) Sum of 25 consecutive cubes
= [ 25(25+1)/2 ]²
= [ 25 × 13 ]²
= ( 325 )²
= 105625
••••
We know that ,
Sum of n consecutive cubes
= [n(n+1)/2]²
1 ) Sum of 10 consecutive cubes
= [10(10+1)/2]²
= [5×6]²
= 30²
= 900
2 ) Sum of 25 consecutive cubes
= [ 25(25+1)/2 ]²
= [ 25 × 13 ]²
= ( 325 )²
= 105625
••••
Answered by
20
Answer:
a) (n(n+1)/2)^2
(10(10+1)/2)^2
(110/2)^2
55^2
3025
b) (25(25+1)/2^2
(25*13)^2
325*325
105625
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