Question

问个化简的问题（k+2)*(9\10)^k >(k+1)*(9\10)^(k-1)(k+2)*(9\10)^k>(k+3

Answer 1

（k+2)*(910)^k >(k+1)*(910)^(k-1)

（k+2)*(910)^(k-1)* )*(910)>(k+1)*(910)^(k-1)

（k+2)*(910)>(k+1)

9(k+2)>10(k+1)

9k+18>10k+10

k(k+3)*(910)^(k+1)

(k+2)*(910)^k>(k+3)*(910)^k*(9/10)

(k+2)>(k+3)(9/10)

10(k+2)9(k+3)

10k+20>9k+27

k>7