Question

Find the sum of first term of an ap whose 2nd and 3rd term are 0and 6 repectivily​

Answer 1

Answer:

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Answer 2

Answer:

third term =6

Tn= a+(n-1)d

6=a+2d

similarly

second term =0

0=a+d

a=-d

putting the value of a in third term

6=-d+2d

6=d

a=-6

SUM OF FIRST N TERMS

Sn = n/2(2a+(n-1)d

=n/2(-12+6n-6)

=n/2(-18+6n)

n(-9+3n

=3n2-9n is answer