the A.P in which 4th term is -15 and 9th term is -30. find the sum of the first 10 number
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Answered by
0
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
Answered by
0
Answer:
= -195....
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