Question

send answer plzz sir for each question
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Answer 1

Answer:

Step-by-step explanation:

17.let the first term of A.P is a and common difference is d

a6=a+5d and

a9=a+8d

from question

6a6=9*a9

6(a+5d)=9(a+8d)

6a+30d=9a+72d

-42d=3a

a=-14d

now a15=a+14d

which is zero ans

18. sn=n/2(2a+(n-1)d)

s20=10(2*2+19*4)

s20=10(80)

800 ans