Question

15, 10, 5, ......In this A.P. sum of first 10 terms is ......

1 point

-75

-125

75

125

​

Answer 1

Answer:

optional (i) - 75

Step-by-step explanation:

AP : 15,10,5..................

So,

a = 15

d = 15 - 10 = -5

n = 10

the Formula used :

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

sn = 10 /2 [ 2(15) + (10 -1 ) (-5) ]

sn = 5 × ( 30+9×-5)

sn = 5 × (30-45)

sn = 5 × (-15 )

sn = -75

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