cau chi can cong vao 2 ve voi 1 thoi day ne:
\(\frac{x+29}{1971}\)+1+\(\frac{x+27}{1973}\)+1+\(\frac{x+25}{1975}\)+1= lam tuong tu
tuong duong x+2000/1971+x+2000/1973+x+2000/1975-x+2000/29-1/27-1/25=0
tuong duong (x+2000)*(1/1971+1/1973+1/1975-1/29-1/27-1/25)=0
tuong duong x+2000=0 (vi 1/1971+1/1973+1/1975-1/29-1/27-1/25>0)
tuong duongx=-2000
Vay...
xong roi do pan
x=2000 nha bn
chuc bn hoc tot
happy new year