एक सीढ़ीनुमा सजावट में नीचे की पंक्ति में (45) बल्ब हैं और हर ऊपर की पंक्ति में (3) बल्ब कम हैं। (8)वीं पंक्ति में कितने बल्ब होंगे?
In a stair-like decoration the bottom row has (45) bulbs and each upper row has (3) fewer bulbs. How many bulbs are in the (8)th row?
Explanation opens after your attempt
B. (24)
Concept
The bulb numbers are \(45,42,39,\ldots\) and \(a_8=24\). Exam tip: keep the difference negative when moving upward.
Why this answer is correct
The correct answer is B. (24). The bulb numbers are \(45,42,39,\ldots\) and \(a_8=24\). Exam tip: keep the difference negative when moving upward.
Exam Tip
बल्बों की संख्या \(45,42,39,\ldots\) है और \(a_8=24\)। परीक्षा में ऊपर जाते समय अंतर ऋणात्मक रखें।
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