Three times a certain number, n, is 21
1 answer:
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Answer:
(-138) is the answer.
Step-by-step explanation:
Perfect square numbers between 15 and 25 inclusive are 16 and 25.
Sum of perfect square numbers 16 and 25 = 16 + 25 = 41
Sum of the remaining numbers between 15 and 25 inclusive means sum of the numbers from 17 to 24 plus 15.
Since sum of an arithmetic progression is defined by the expression
Where n = number of terms
a = first term of the sequence
d = common difference
= 4(34 + 7)
= 164
Sum of 15 + = 15 + 164 = 179
Now the difference between 41 and sum of perfect squares between 15 and 25 inclusive =
= -138
Therefore, answer is (-138).