the 14th term of an ap is twice the 8th ternm. if the 6th term is 8 then find the sum of it's first 20 terms
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Answered by
0
Answer:
340
Step-by-step explanation:
a14= a8
a6=8
a+5d=8
a14=a8
a+13d=a+7d
by solving we get a=-d
substitute the value of a in
-d+5d =8
solving it we get
d=2and a=-2
thus sum =340
Answered by
1
continuation......
S20= 10*(-4+38)
S20=10*34
S20=340
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