Question

The sum of n natural numbers
is 5h²4 4n- find its 8th term.
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Answer 1

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Answer 2

Answer:

the value is S8 is 79

Step-by-step explanation:

given that Sn=5n^2+4n

n=8

S8=(5*8*8)+(4*8)

=320+32

=352

S8 refers the sum of the first 8 members of the given sequence, which is equal to the value of 352.

S7 refers the sum of the first 7 numbers of the given sequence, which is equal to the value of 273.

n=7

S7=(5*7*7)+(4*7)

=245+28

=273.

by subtracting the sum of first 8 numbers by the sum of first 7numbers to get the value of S8.

S1+S2+S3+S4+S5+S6+S7+S8= –S1+S2+S3+S4+S5+S6+S7=2

S8=79

therefore the term S8=79