Math, asked by mussaddiq60, 1 year ago

Find
the number of the term
18, 15 1/2, 13.......-47

Answers

Answered by RekhaSaini
19

Answer:

A=18

d =-5/2

an=-47

an=a+(n-1)d

-47=18+(n-1)-5/2

-47-18=n-1(-5/2)

-65*-2/5=n-1

-13*-2

26+1 =n

27=n

Answered by Anonymous
58

\Large{\underline{\underline{\bf{Given:-}}}}

first \: term \: (<strong>a</strong>) = 18 \\  \\common \: difference \:  (d) = a_2 - a_1  \\  \\  = 15 \frac{1}{2}  - 18 \\  \\  =  \frac{31}{2}  - 18 \\  \\  =  \frac{31 - 36}{2}  \\  \\  =  \frac{ - 5}{2}  \\  \\n ^{th} \: term \: of \: airthmetic \: progression \: series \: (  a_n )=  - 47

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\Large{\underline{\underline{\bf{To \: Find:-}}}}

 n \: = \: ?

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{\bold{\underline{\underline{As \: we \: know \: , \: for \: an \: airthmetic \: progresssion :-}}}}

</u></strong><strong><u>⟹</u></strong><strong><u>a_n = a + (n - 1)d \\  \\  </u></strong><strong><u>⟹</u></strong><strong><u>- 47 = 18 + (n - 1)   \frac{ - 5}{2}  \\  \\</u></strong><strong><u>⟹</u></strong><strong><u>  - 47  - 18 = (n - 1) \frac{ - 5}{2}  \\  \\</u></strong><strong><u>⟹</u></strong><strong><u>  - 65 = (n - 1) \frac{ - 5}{2}  \\  \\</u></strong><strong><u>⟹</u></strong><strong><u>  \frac{ - 65 \times 2}{ - 5}  = (n - 1) \\  \\  </u></strong><strong><u>⟹</u></strong><strong><u>\frac{ - 130}{ - 5}  = (n - 1) \\  \\ </u></strong><strong><u>⟹</u></strong><strong><u>26 = n - 1 \\  \\</u></strong><strong><u>⟹</u></strong><strong><u> 26 + 1 = n \\  \\ </u></strong><strong><u>⟹</u></strong><strong><u>27 = n

\huge\boxed{n \: = \: 27}

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{\bold{\underline{\underline{Therefore \: , \: this \: given \: Airthmetic \: progression\: has \: 27 \: terms \: in \: it:-}}}}

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\Large{\underline{\underline{\bf{Thanks:-}}}}

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