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