(Solved): please solve!! Exercise \( 1 \mathrm{~K} \) 1 In an arithmetic sequence, the b i Find \( u_{28^{\cir ...

Exercise \( 1 \mathrm{~K} \) 1 In an arithmetic sequence, the b i Find \( u_{28^{\circ}} \). first term is \( -8 \) and the sum of ii Hence, find \( S_{28^{\circ}} \). the first 20 terms is 790 . c Find how many terms it takes a Find the common difference. for the sum to exceed \( 2000 . \)