(Q2).Find the sum of indicated number of terms in each of the following A.Ps.
(i) -0.5, -1.0, -1.5,…..; 10 terms.
Given : -0.5, -1.0, -1.5, …. S
10
a = –
d = t
2
– t
1
= (-
) – (-
)
⇒ S
n
=
n
2
[2a + (n-1)d]
⇒ S
10
=
2
[2×(-
) + (
-1)×(-
)]
=
[-
+
×(-
)]
=
[-
-
]
=
× (-
) = -
Clear