Question

the terms 3,6,9,12,.........81 find the 21 st term of given AP
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Answer 1

an=a+(n-1)d

=3+(21-1)3

=3+(20)3

=3+60

=63

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Answer 2

Answer:

the 21st term of the AP=63

Step-by-step explanation:

3,6,9,12................81

To find 21 st term:

first term(a)=3

difference(d)=second term-first term

                    d  =6-3

                    d = 3

number of term(n)=21

formula:

n th term=a+(n-1)d                          --equation 1      

put the given values in equation 1    

21 st term=3+(21-1)*3

21 st term=3+20*3

21 st term=3+60

21 st term=63

therefore

the 21 st term of the AP = 63