Question

Rezolvați exercițiul 5 prin progresie

Answer 1

asta e o progresie geometrica

q(ratia)=bn-bn-1

q=$\frac{1}{5^{2} }$

S=b1x$\frac{q^{n} -1}{q-1}$

b1=1/5

bn=b1xq^(n-1)

$\frac{1}{5^{99} }$=$\frac{1}{5}$x$\frac{1}{5^2} ^{n-1}$ inmultim cu 5

$\frac{1}{5^{98} }$=$\frac{1}{5^2} ^{n-1}$

98=2n-2

2n=96

n=48

S=$\frac{1}{5}$x($\frac{1}{5}$^{48} -1)/{$\frac{1}{5}$-1}

S=$\frac{-1}{4}$x(5^(-48)-1)

Sper sa fie corect. Scuze daca am gresit ceva.