Fill in the blanks in the following table, given that a is the first term, $d$ the common difference and $a_n$ the nth term of the AP:
"

AcademicMathematicsNCERTClass 10

To do:

We have to fill in the blanks.

Solution:

(i) $a=7, d=3, n=8$

We know that,

$a_{n}=a+(n-1) d$

$a_{8}=7+(8-1) 3$

$=7+21$

$=28$

(ii) $a=-18, n=10, a_{n}=0$

We know that,

$a_{n}=a+(n-1) d$

$\Rightarrow 0=-18+(10-1) d$

$18=9d$

$d=2$

(iii) $d=-3, n=18, a_{n}=-5$

We know that,

$a_{n}=a+(n-1) d$

$-5=a+(18-1)(-3)$

$-5=a-51$

$a=-5+51$

$a=46$

(iv) $a=-18.9, d=2.5, a_{n}=3.6$

We know that,

$a_{n}=a+(n-1) d$

$3.6=-18.9+(n-1) 2.5$

$3.6+18.9=(n-1) 2.5$

$\frac{22.5}{2.5}=n-1$

$9=n-1$

$n=9+1$

$n=10$

(v) $a=3.5, d=0, n=105$

We know that,

$a_{n}=a+(n-1) d$

$=3.5+(105-1) 0$

$=3.5+0$

$=3.5$

raja
Updated on 10-Oct-2022 13:20:18

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