Q1. If the first term of an A.P. is 3 and the sum of its first four terms is equal to one-fifth of the sum of the next four terms, then the sum of the first 20 terms is equal to (1) −1080 (2) −1020 (3) −1200 (4) −120
What This Question Tests
This question tests the basic understanding and application of formulas for the sum of n terms in an arithmetic progression to find the common difference and then the sum of first 20 terms.
Concepts Tested
Formulas Used
Sn = n/2 * (2a + (n-1)d)
📚 NCERT Sections This Tests
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Physics Class 11 · Chapter 2
2.1 Two charges 5 × 10–8 C and –3 × 10–8 C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.
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📋 Question Details
- Chapter
- Sequences & Series
- Topic
- Arithmetic Progression (AP)
- Year
- 2025
- Shift
- 23 Jan Shift 1
- Q Number
- Q1
- Type
- MCQ
- NCERT Ref
- Class 11 Mathematics Ch 9: Sequences and Series
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