A = 3+ 3/5+ 3/25+ 3/125+ 3/625
A = 3/1+ 3/5+ 3/25+ 3/125+ 3/625
A = 1875/625 + 375/625 + 75/625 + 15/625 + 3/625
A = 3 + 0,6 + 0,12 + 0,024 + 0,0048
A = 3,6 + 0,12 + 0,024 + 0,0048
A = 3,72 + 0,024 + 0,0048
A = 3,744 + 0,0048
A = 3,7488
A = 3 + \(\dfrac{3}{5}\) + \(\dfrac{3}{25}\) + \(\dfrac{3}{125}\) + \(\dfrac{3}{625}\)
5\(\times\)A = 15 + 3 + \(\dfrac{3}{5}\) + \(\dfrac{3}{25}\) + \(\dfrac{3}{125}\)
5 \(\times\) A - A = 15 + 3 + \(\dfrac{3}{5}\) + \(\dfrac{3}{25}\) + \(\dfrac{3}{125}\) - (3 + \(\dfrac{3}{5}\) + \(\dfrac{3}{25}\) + \(\dfrac{3}{125}\) + \(\dfrac{3}{625}\))
4 \(\times\) A = 15 + 3 + \(\dfrac{3}{5}\) + \(\dfrac{3}{25}\) + \(\dfrac{3}{125}\) - 3 - \(\dfrac{3}{5}\) - \(\dfrac{3}{25}\) - \(\dfrac{3}{125}\) - \(\dfrac{3}{165}\)
4 \(\times\) A = (15 - \(\dfrac{3}{625}\)) + (3 - 3) + (\(\dfrac{3}{5}\) - \(\dfrac{3}{5}\)) + (\(\dfrac{3}{25}-\dfrac{3}{25}\)) + (\(\dfrac{3}{125}\)-\(\dfrac{3}{125}\))
4 \(\times\) A = \(\dfrac{9372}{625}\)
A = \(\dfrac{9372}{625}\) : 4
A = \(\dfrac{2343}{625}\)