(160-20p)*p=300
160p - 20p^2 - 300=0
-p^2+80p-150=0
D=6400-6000=400
p1=30
p2=50
Ответ: р=50
(9−1)*(9+1)*(92+1)*(94+1)*(98+1)−916+42 = (81-1)*93*95*99 - 916 + 42 =
80*93*95*99 - 874 = 7440*9405 - 874 = 69973200 - 874 = 69972326
Вариант D.....,.........................
А)1) 1+3 =4
2)2:4=1/2
3)1+1/2=1,5
4)1:1,5=2/3
5) 1+2/3=1,2/3
Б)1)1+3=4
2)2:4=0,5
3)1-0,5=0,5
4)1:0,5=2
5)1-2=-2