Question

The algebraic expression of an arithmetic sequence is 3-5n ?

Find its common difference?

Find its first term?

Form a sequence ?

Find the sum of 'n' term ?

Answer 1

Answer:

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Answer 2

Step-by-step explanation:

1st term-

a1 = 3 - (5×1)

a1 = 3 - 5

a1 = -2

2nd term-

a2 = 3 - 5×2

a2 = -7

3rd term-

a3 = 3 - 5×3

a3 = -12

Common Difference-

a2 = a + d = -7

d = -7 - (-2)

d = -7 + 2 = -5

d = -5

Sequence-

-2, -7, -12, -17, -22...

Sum of 'n' terms-

$S_n$ = n/2 (a + l)

$S_n$ = n/2 (-2 + 3 - 5n)

$S_n$ = n/2 (1 - 5n)

$S_n$ = (n - $5n^2$)/2