Формула арифметической прогрессии:
1)a1=-8; a2=-1; d=7; a51=-8+7*50=342;
2)a1=10; a2=6; d=-4; a101=10-4*100=390
3)a1=20; a2=13; d=-7; a81=20-7*80=-540
4)a1=10; a2=3; d=-7; a101=10-7*100=-690
5)a1=30; a2=24; d=-6; a51=30-6*50=-270
6)a1=1; a2=3; d=2; a11=1+2*10=21
7)a1=-6; a2=-2; d=4; a16=-6+4*15=54
1)a1=-8; a2=-1; d=7; a51=-8+7*50=342;
2)a1=10; a2=6; d=-4; a101=10-4*100=390
3)a1=20; a2=13; d=-7; a81=20-7*80=-540
4)a1=10; a2=3; d=-7; a101=10-7*100=-690
5)a1=30; a2=24; d=-6; a51=30-6*50=-270
6)a1=1; a2=3; d=2; a11=1+2*10=21
7)a1=-6; a2=-2; d=4; a16=-6+4*15=54