यदि समान्तर श्रेणी \(c-5,c+1,c+7,\ldots\) का (21)वां पद (139) है तो (c) का मान क्या होगा?
If the (21)st term of the AP \(c-5,c+1,c+7,\ldots\) is (139), what is the value of (c)?
Explanation opens after your attempt
B. (24)
Concept
Here (d=6). \(139=c-5+20\times6=c+115\), so (c=24).
Why this answer is correct
The correct answer is B. (24). Here (d=6). \(139=c-5+20\times6=c+115\), so (c=24).
Exam Tip
यहां (d=6)। \(139=c-5+20\times6=c+115\) इसलिए (c=24)।
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