Question

if the sum of n terms of an AP is 2n² +5n,then find 4th term​

Answer 1

Answer:

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Answer 2

• Given sum of nth term is 2n²+5n

Let us find the sum of 1st term which is equal to the first term (a) of an AP

S¹=2×1²+5×1=7

Let us also find S² which is the second term of the AP I,e a+d( d= common difference)

S² = 2×2²+5×2=18

From this we can calculate d which is as follows

S²=a+d

18=7+d

d=18-7=11

Now ,The 4th term of the AP is

t⁴= a+(n-1)×d

=> t⁴=7+3d

=> t⁴=7+ 3×11

=> t⁴=7+33=40

•°• The 4th term of the AP is 40✓✓