Please help me with number 8a and b
1 answer:
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Answer:
1800
Step-by-step explanation:
The sum to n terms of an arithmetic sequence is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
Here a₁ = - 27 and d = 6, thus
=
[ (2 × - 27) + (29 × 6) ]
= 15( - 54 + 174)
= 15(120)
= 1800