Answer: \(S_{10} = -195\)
\(a + 3d = -15\), \(a + 8d = -30\). Subtracting: \(5d = -15\), \(d = -3\); \(a = -15 + 9 = -6\).
\[S_{10} = \frac{10}{2}[2(-6) + 9(-3)]\]\[= 5(-12 - 27) = -195\]1 answer
Doubtly AI
· 24 Oct 2026
AI-verified · Oct 2026
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