Question

) Find the sum of the mnatural numbers 1, 2, 3 · · · 10

Using this calcualte the sum of the terms of the sequence 7, 14, 21, 28 · · · 70

pls show the method of getting this answer...

if it is correct only I will mark you brillinist

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Answer 1

Answer:

7 * ( Sum of first 10 natural numbers) = 7 * 55 = 385

Step-by-step explanation:

1st problem...

• Alright you know that sum of first n natural numbers is n*(n+1)/2.
• Here n is 10 so, sum =( 10*(10+1) ) / 2 = 55

Solving second problem using 1st problem

• You know that sum of the terms of sequence is called series.
• Here the series is 7 + 14 + 21 + ... + 70
• Taking 7 common from all the terms of the series will look something like this. 7*( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)
• Now from the first problem you know that 1 + 2 + 3 +...+ 10 = 55
• So, you can use that result here and here comes your answer which is 7*55 = 385

Hope you get it!!