cos(2x)=1-2sin^2(x)-формула двойного аргумента
cos(п/2-x)=sin(x)-формула приведения
1-2sin^2(x)=1-sin(x)
-2sin^2(x)+sin(x)=0
sin(x)(-2sin(x)+1)=0
sin(x)=0 sin(x)=1/2
x=-2п x=-7п/6
x=-13п/6
3*1(2*1-5)-8*1(4*1-3)=3*(-3)-8=-17
Х^2- 4x- 45 = ( x+5)(x- 9)
x^2- 4x -45 = 0
D= 16- 4* (-45)= 196
x1= (4 - 14 ) / 2 = - 5
x2= (4+14) / 2 = 9
1)(3/4ab^2+2/3a^2)^3=27/64a^3v^6+8/27a^6
2)(1/2a+ab^2)^3=1/8a^3+a^3b^6
3)(1/3ab-c)^3=1/27a^3b^3-c3
4)(1/4x-yz)^3=1/64x^3-y^3z^3
5)(a^3x+ax^2)^3=a^9x^3+a^3x^6
6)(b^2y+by^2)^3=b^6y^3+b^3y^6
7)(0,4a^5-0,3a^3)^3=0,064a^15-0,027a^9
8)(0,5x^2-0,2x^5)^3=0,125x^6-0,008x^15
<span>489*x*37*y=</span>489*37*х*у=18093*ху