[" How many terms of the series "1+2+2^(2)+2^(3)+......" ."],[" must be taken to make "511" ."]

How many terms of the sequence -12,-9, -6, -3, ..... must be taken to make the sum 54 ?

Sum to n terms of the series 1+(1+2)+(1+2+3)+.. ..

How many terms of the series 1+3+3^(2)+3^(3)+3+....+3^(n-1) must be taken to make the sum equal to 3280.

How many terms of the series 2 +6+ 18+ ... must be taken to make the sum equal to 728?

How many terms of the series –12, – 9, – 6,... must be taken that the sum may be 54?

How many terms of the series 2+6+18+ . . . . . . . . . . . Must be taken to make the sum equal to 728 ?

How many terms of the series 20+19(1)/(3)+18(2)/(3)+"...." must be taken to make 300? Explain the double answer.