\(यदि (U={1,2,\ldots,81}), (A={x:x \in U,x\) पूर्ण वर्ग है}), तो (A') में (9) से विभाज्य संख्याओं की संख्या कितनी है?
\(If (U={1,2,\ldots,81}), (A={x:x \in U,x\) is a perfect square}), how many numbers divisible by (9) are in (A')?
Explanation opens after your attempt
Correct Answer
A. (4)
Concept
Numbers divisible by (9) are (9,18,27,36,45,54,63,72,81). Removing squares (9,36,81) leaves (6) members.
Why this answer is correct
The correct answer is A. (4). Numbers divisible by (9) are (9,18,27,36,45,54,63,72,81). Removing squares (9,36,81) leaves (6) members.
Exam Tip
(9) से विभाज्य संख्याएं (9,18,27,36,45,54,63,72,81) हैं। इनमें वर्ग (9,36,81) हटेंगे, इसलिए (6) नहीं बल्कि (6) सदस्य बचते हैं।
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