3∛x=x-2
27x=x³-6x²+12x-8
27-x³+6x²-12x+8=0
15x-x³+6x²+8=0-x³+6x²+15x+8=0
-x³-x²+7x²+7x+8x+8=0
-x²×(x+1)+7x×(x+1)+8(x+1)=0
-(x+1)×(x²-7x-8)=0
-(x+1)×(x²+x-8x-8)=0
-(x+1)×(x×(x+1)-8(x+1))=0
-(x+1)×(x+1)×(x-8)=0
-(x+1)²×(x-8)=0
-(x+1)²=0
x-8=0
x₁=-1,x₂=8
9x^2-7x-2=0
D=49-4(9*(-2)=49+72=121
x1 = (7+11)/18=1
x2 = (7-11)/18 = -4/18 = -2/9
Ответ: x1 = 1; x2 = -2/9
1-sinacosa/tga=1-sinacosa/(sina/cosa)=
=1-sinacosa(cosa/sina)=1-cos²a=sin²a
tga≠0,a≠kπ,k∈Z
(tga=sina/cosa, sin²a+cos²a=1)
(3/4)ⁿ>1 при n∈(-∞;0)
(3/4)ⁿ<1 при n∈(0; +∞)
(3/4)ⁿ=1 при n=0;