Question

the A.P in which 4th term is -15 and 9th term is -30. find the sum of the first 10 number​

Answer 1

Answer:

S10=-195

Step-by-step explanation:

Let first term is a and common difference=d

then a4=a+3d=-15..........(1)

a9=a+8d=-30....................(2)

subtracting (1) from(2) we get

5d=-30+15=-15

d=-3

from(1)

a+3(-3)=-15

a-9=-15

a=-6

Now

S10=10/2{ 2*(-6) +9(-3) }

=5( -12-27)

=5*(-39)

=-195

Answer 2

Answer:

= -195....

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