Xˇ4+yxˇ3-x-y=xˇ3(x+y) -(x+y).1=(x+y)(xˇ3-1)=(x+y)(x-1)(xˇ2+x+1)
Х=2у-3
7(2у-3)-10у=7
4у-21=7
4у=28
у=7
х=2×7-3=11
3x^2-10x+3=0
D=(-10)^2-4*3*3=64
x1=(10-8)/6=1/3
x2=(10+8)/6=3
3(x-1/3)(x-3)= (3x-1)(x-3)
Решение
cosπ/12 - cos5π/12 = - 2*sin[(π/12 + 5π/12)/2]*sin[(π/12 - 5π/12)/2] =
= 2*sin(π/4)*sin(π/6) = 2*(√2/2)*(1/2) = √2/2