Cos(354) = cos(360 - 4) = cos(4)
1. D=b^2-4ac=25-4*(-50)=225=15^2
y1=5, y2=-10
2. <span>4x^2-100=0
</span><span>4x^2=100
</span>x^2=25
x1=5; x2=-5
2 * V1*V2 2 * 60 * 90 10800
V ср. = ------------------------ = ----------------------- = ------------------------ = 72 км/ч
V1 + V2 60 + 90 150
5у=4-7
5у=-3
у=-3:5
у=-0,6
5*-0,6+7=4
4=4
8х=5-2+3
8х=6
х=6:8
х=0,75
8*0,75-3=5-2
6-3=3
3=3