Answer:
S₄₉ = 8820
Explanation:
the sum to n terms of an arithmetic series is
=
[ 2a₁ + (n - 1)d ]
where a₁ is the first term and d the common difference
here a₁ = 36 and d = a₂ - a₁ = 42 - 36 = 6 , then
S₄₉ =
[ (2 × 36) + (48 × 6) ]
= 24.5 (72 + 288)
= 24.5 × 360
= 8820