ОДЗ: s≠720, s≠200
720(2s-400)=(s+400)*(s-720)
1440s-288000=s²-720s+400s-288000
1440s-s²+720s-400s=0
-s²+1760s=0
s(s-1760)=0
s1= 0
s2= 1760
ОДЗ: s≠720, s≠200
720(2s-400)=(s+400)*(s-720)
1440s-288000=s²-720s+400s-288000
1440s-s²+720s-400s=0
-s²+1760s=0
s(s-1760)=0
s1= 0
s2= 1760