Question

9. Which terın of the AP 18,23,28,33.is 982
a. 15th
b. 16th
c. 17th
d. 18th​

Answer 1

Given :

An AP 18 , 23 , 28 , 33 , .....

Options :

a. 15th

b. 16th

c. 17th

d. 18th

Solution :

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nth term of an AP is given by ,

$\pink{\bigstar}\ \; \sf a_n=a+(n-1)d$

Where ,

• a denotes first term
• n denotes nth term value
• d denotes common difference

★══════════════════════★

Here ,

a = 18

d = 23 - 18 = 5

n = ?

aₙ = 98

➠ 98 = 18 + (n - 1)5

➠ 98 = 18 + 5n - 5

➠ 5n + 18 = 98 + 5

➠ 5n + 18 = 103

➠ 5n = 103 - 18

➠ 5n = 85

➠ n = 17

17th term of the given AP is 98

Option C

Answer 2

$\large\pink \dag \bf \: According \: to \: question$

An AP 18 , 23 , 28 , 33 , .....

$\bf \: so$

a = 18

d = 23 - 18 = 5

n = ?

aₙ = 98

$\bf★ \pink FORMULA \: \pink USED$

$\implies\ \; \sf a_n=a+(n-1)d$

$\bf \: put \: the \: given \: value \: in \: this \: formula </h3><h3>$

$\bf \: 98 = 18 + (n - 1)5 \\ </p><p></p><p> \bf \: 98 = 18 + 5n - 5 \\ </p><p></p><p> \bf \: 5n + 18 = 98 + 5 \\ </p><p></p><p> \bf 5n + 18 = 103 \\ </p><p></p><p> \bf \: 5n = 103 - 18 \\ </p><p></p><p> \bf 5n = 85 \\ </p><p></p><p> \bf n = 17</p><p></p><p>$

Option C