Question

The 11th term of the AP: -5,-5/2,0 ,5/2, .... is

Answer 1

Answer:

a (11)= a+10d= -5+(10)*5/2= -5+25= 20

Answer 2

ANSWER = (B) 20

$AP = - 5 ,\: \frac{ - 5}{2} ,\: 0 , \: \frac{5}{2} ...$

$\sf \: Common \: difference = \frac{ -5 }{2} - ( - 5)$

$\: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{5}{2}$

$\sf \: General \: formula = \: dn \: + (f - d)$

where ,

• d = common difference
• f = first term
• n = number of terms

Here ,

$\sf \: n {}^{th} term \: = \frac{5}{2} n \: + ( - 5 - \frac{5}{2} )$

$\sf \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \frac{5}{2} n \: - \frac{15}{2}$

11th term

$\implies \: \frac{5}{2} \times 11 - \frac{15}{2}$

$\implies \: \: \frac{55 - 15}{2}$

$\implies \: \frac{40}{2}$

$\implies \: 20$