5m-2 5m+2 (5m-2)² -(5m+2)² (5m-2+5m+2)(5m-2-5m-2)
-------- - ---------- = ---------------------- = -------------------------------------- =
5m+2 5m-2 25m² - 4 25m²-4
(10m)(-4) 40m
= ------------------------- = - ------------
25m²-4 25m²-4
40m 12-75m² 2*(12-75m²) 24
- ---------------- * ---------------- = - ------------------------ = - --------- +6 =
25m² 20m 25m² 25m²
= 6- 0.96/m²
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пусть учеников n 120/n каждому
n+2 120/(n+2)
120 120 2
----------- - -------- = 120* -------- = 2
n n+2 n(n+2)
n²+2n-120 =0 корни √D =√(4+480)=22
n1=0.5(-2+22)=10 n2=0.5(-2-22)= - 12 не годится n>0
ответ 10 учеников