Question

find the sum of the AP 25+30+35+......11th term

Answer 1

a=25
d=5
a11=a+(10d)
= 25+10(5)
=25+50
=75
s11=n/2(a +a11)
=11/2(25+75)
=11/2(100)
=11(50)
=550
your answer is 550


hope it helps

Answer 2

Hey !!!

a₁ = 25

a₂ = 30

n = 11

d = a2 - a1 = 30 - 25 = 5

we know a formula

sn = n/2 [2a + ( n - 1) d ]

s11 = 11/2 [( 2* 25 + ( 11 - 1) 5

=> 11 /2 [ 50 + 50 ]

=> 11* 50

=> 550

sn = 550
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Hope it helps you !!!

@Rajukumar111