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  • The 11th term of the AP: –5, \frac{-5}{2},0,\frac{5}{2}, .is

The 11th term of the AP:

-5, \frac{-5}{2},0,\frac{5}{2}, \ldots ..is\\

(A) –20

(B) 20

(C) –30

(D) 30

Answers (1)

Here AP is

 -5, -\frac{5}{2},0,\frac{5}{2}, $ \ldots $ $ \ldots $ ..\\
 Here

\\a\textsubscript{1 }= - 5, a\textsubscript{2}= -\frac{5}{2} \\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ $(Common difference) $d = a\textsubscript{2} - a\textsubscript{1\ \ \ }\\ = -\frac{5}{2}-(-5) \\ = -\frac{5}{2}+5 \\ \begin{aligned} & =\frac{-5+10}{2} \\ & =\frac{5}{2} \\ \end{aligned}

\\ a \textsubscript{n} = a\textsubscript{1} + (n - 1).d\\ Put\ n = 11\\ a\textsubscript{11} = a\textsubscript{1} + (11 - 1).d \\ a\textsubscript{11} = - 5 + (10). (5/2)\\ \ \ \ \ = - 5 + 5.(5)\\ \ \ \ \ = - 5 + 25\\ \ \ \ = 20\\

Hence option B is correct.

Posted by

infoexpert21

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