Lucy is working with a series whose first term is 12 and that is generated by the equation t(n) = −9 + 21n. The sum of her series is 3429. How many terms are in her series? *hint: the last term can be written as -9 + 21n if we say there are n terms. You will need to solve a quadratic equation to solve for n.

18termsare in herseries## What is Arithmetic progression series?

Arithmetic Progression(AP) is asequenceofnumbersin order inwhichthedifferenceof anytwo consecutivenumbers is a constant value.t(n)= −9 + 21n=la=12,Sum= 3429Sumof series =34297n² + n- 2286=0n= 18or n= -127/718 termsin theseries.serieshere:#SPJ1