JEE Mains · Maths · STD 11 - 8. sequence and series
In an arithmetic progression, if \(S_{40}=1030 \text { and } S_{12}=57 \text {, then } S_{30}-S_{10} \text { is equal to : }\)
- A 525
- B 510
- C 515
- D 505
Answer & Solution
Correct Answer
(C) 515
Step-by-step Solution
Detailed explanation
\(\begin{aligned} & S_{40}=1030 \Rightarrow \frac{40}{2}[2 a+39 d]=1030 \\ & \Rightarrow \quad 2 a+39 d=\frac{103}{2}....(1) \\ & \quad S_{12}=57 \Rightarrow \frac{12}{2}[2 a+11 d]=57 \\ & \Rightarrow \quad 2 a+11 d=\frac{57}{6}...(2) \end{aligned}\) Equation (1) - equation (2)…
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