Tg²a+ctg²a)=(tga+ctga)²-2=3²-2=9-2=7
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(tga+ctga)=tg²a+2*tga*ctga+ctg²a=tg²a+2*ctg²a
X(25x^2-10x+1)=0
x(5x-1)^2=0
x=0 (5x-1)^2=0
x=0 x=1/5
sin5x+sinx=0
2sin3xcos2x=0
2sin3x=0 3x=πn,n∈z x=πn/3,n∈z
cos2x=0 2x=π/2+πn,n∈z x=π/4+πn/2,n∈z
Ответ: x1=πn/3,n∈z; x2=π/4+πn/2,n∈z
97-x=x-55
97+55=x+x
152=2x
x=152:2
<span>x=76%</span>
= - x^5 + 15x^4 - 90x^3 + 270x^2 - 405x + 243