Question

Tn+1=35-2Tn, T1=5 what is T20?

Answer 1

Answer: 3,495,265

Explanation:

`T_(n+1)=35-2T_n\quad and\quad T_1=5, then\\T_(1+1)=35-2(T_1)\implies T_2=35-2(5)\implies T_2=25\\T_(2+1)=35-2(T_2)\implies T_3=35-2(25)\implies T_3=-15\\T_(3+1)=35-2(T_3)\implies T_4=35-2(-15)\implies T_4=65\\T_(4+1)=35-2(T_4)\implies T_5=35-2(65)\quad \implies T_5=-95\\T_(5+1)=35-2(T_5)\implies T_6=35-2(-95)\implies T_6=225\\.\qquad \qquad \qquad \qquad \qquad \qquad \downarrow\\.\qquad \qquad \qquad \qquad \qquad \qquad \downarrow\\.\qquad \qquad \qquad \qquad \qquad \qquad \downarrow`

`T_(18+1)=35-2(T_(18))\implies T_(19)=35-2(873,825)\implies T_(19)=-1,747,615\\T_(19+1)=35-2(T_(19))\implies T_(20)=35-2(-1,747,615)\implies T_(20)=3,495,265`