১.
$\{d\over dx\}(cos \{x\over 5\})$ =কত?
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$-sin \{x\over 5\}$
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$sin \{x\over 5\}$
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$-\{1\over 5\}sin \{x\over 5\}$
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$\{1\over 5\}sin \{x\over 5\}$
ব্যাখ্যা
$\frac{d}{d x}\left(\cos \frac{x}{5}\right)=-\sin \frac{x}{5} \frac{d}{d x}\left(\frac{x}{5}\right)=-\frac{1}{5} \sin \frac{x}{5}$.