Find the sum of first 20 terms of an A.P, in which 3rd term is 7 and the 7th term is two more than thrice of its 3rd term.
Answers
Answered by
17
a+2d=7----------1)
a+6d=3(a+2d)+2
a+6d=23-------------2)
1)-2)
-4d=-16
d=4
a+2d=7(from 1))
a+8=7
a=-1
=n/2[2a+(20-1)d]
=10[-2+76]
=10[74]
=740
THEREFORE THE SUM IS 740
HOPE THIS HELPS YOU!!
a+6d=3(a+2d)+2
a+6d=23-------------2)
1)-2)
-4d=-16
d=4
a+2d=7(from 1))
a+8=7
a=-1
=10[-2+76]
=10[74]
=740
THEREFORE THE SUM IS 740
HOPE THIS HELPS YOU!!
laksssss:
Pls mark as brainliest
Answered by
0
Answer:
yo
Step-by-step explanation:
Similar questions