Ab^2-2ab+ac^2=a(b^2-2ac+c^2)=a(b-c)^2
Сtgx*cosx*(-sinx)=-cos²x=-(1-0,09)=-0,91
2а)
nєZ.
xє[2π/3 + 2πn; π+2πn], nєZ.
2b)
nєZ.
xє[π/4 +πn; π/2+πn], nєZ.
3.
найдем нули функции
соs(x)=0 при х1=π/2 +2πn, nєZ,
x2=3π/2 +2πn, nєZ.
2cos(x)+1=0
cos(x)=-1/2
x1=2π/3 +2πn, nєZ,
x2=4π/3+2πn, nєZ.
___o_____o_____o_____o____
..+..π/2...-...2π/3..+..4π/3...-...3π/2..+.
xє(π/2+2πn;2π/3+2πn)U(4π/3+2πn;3π/2+2πn), nєZ.
log2x+6log2^2x+9log2^3x=14
log2x+6*1\2log2x+9*1\3log2x=14
log2x+3log2x+3log2x=14
log2x+log2x^3+log2x^3=14
log2(x*x^3*x^3)=14
log2x^7=14
x=