Find the 21st term in the arithmetic sequence 9 3 –3

ANSWERS

2016-09-25 09:08:51

it decreases by 6 each time first term is 9 an=a1+d(n-1) a1=first term d=common differnence so first term or a1 is 9 common differnce is -6 an=9-6(n-1) 21st term a21=9-6(21-1) a21=9-6(20) a21=9-120 a21=-111 the 21st term is -111

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