Question

-3, 2, 7, 12,17,....
Sn=? , t6= ? , +9=?​

Answer 1

the sum of first 10 terms of the given A.P is 195

Step-by-step explanation:

, a = –3

common difference is the difference between any two consecutive terms.

hence, d = 2 – (–3)

d = 2 + 3

d = 5

We have to find the sum of first 10 terms. So, put n = 10,

\begin{gathered}\tt S_{10}=\dfrac{10}{2}[2(-3)+(10-1)(5) \\ \tt S_{10} = 5[-6+9(5)] \\ \tt S_{10}=5[-6+45] \\ \tt S_{10}=5(39) \\ \tt S_{10} = 195\end{gathered}

S

10

=

2

10

[2(−3)+(10−1)(5)

S

10

=5[−6+9(5)]

S

10

=5[−6+45]

S

10

=5(39)

S

10

=195

Therefore, the sum of first 10 terms of the given A.P is 195

Answer 2

Answer:

sn=n/2(5n-11) ; t6=22 ; +9=not possible in A.P

Step-by-step explanation:

a = -3 ; d = 5

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

sn=n/2[ (2 x -3) + ( n -1 ) 5]

sn=n/2[-6+5n-5]

sn=n/2(5n-11)

t6=a+(n-1)d

t6= -3+(6-1) x 5

t6=-3+(5x5)

t6= 25-3

t6=22