Subiecte "Lumina Math"

moldovan ana · Post by **moldovan ana** » Tue Dec 08, 2009 9:02 am

Va rog sa-mi aratati cum se rezolva urmatoarea problema, nr.28/varianta A, clasa 7-a tot de la Lumina Math :

Gasiti primele 3 zecimale nenule ale numarului 12345678...181920 / 20191817...654321 unde "/" inseamna linia de fractie.

Eu personal ma tot gandesc cum a alcatuit comisia cele 40 de subiecte propuse spre rezolvare in 120 minute, deci in medie 3 minute pt. fiecare problema?

Marius Mainea · Post by **Marius Mainea** » Tue Dec 08, 2009 11:02 pm

\( 0,6113...=\frac{12345}{20192}< x<\frac{12346}{20191}=0,6114... \)

deci \( x=0,611...... \)

moldovan ana · Post by **moldovan ana** » Wed Dec 09, 2009 9:29 am

Daca am inteles bine avem:
1234500...0 < 123456...181920 < 1234600...0
2019100...0 < 20191817...654321 < 2019200...0
dar cum ati stablit dupa cate cifre trebuie rotunjit prin lipsa si prin adaos?

Marius Mainea · Post by **Marius Mainea** » Wed Dec 09, 2009 12:24 pm

Am rotunjit in asa fel incat primele trei zecimale sa coincida.