![x^{3} +33=-2x \\ x^{3}+2x+33=0 \\ x^{3} +11x-9x+33=0 \\ x(x^{2} -9)+11(x+3)=0 \\ x(x-3)(x+3)+11(x+3)=0 \\ (x^{2} -3x+11)(x+3)=0 \\ x+3=0 \\ x_{1} =-3 \\ x^{2} -3x+11=0 \\ D<0](https://tex.z-dn.net/?f=+x%5E%7B3%7D+%2B33%3D-2x+%5C%5C+%0A+x%5E%7B3%7D%2B2x%2B33%3D0+%5C%5C+%0A+x%5E%7B3%7D+%2B11x-9x%2B33%3D0++%5C%5C+%0A+x%28x%5E%7B2%7D+-9%29%2B11%28x%2B3%29%3D0+%5C%5C+%0Ax%28x-3%29%28x%2B3%29%2B11%28x%2B3%29%3D0+%5C%5C+%0A+%28x%5E%7B2%7D+-3x%2B11%29%28x%2B3%29%3D0+%5C%5C+%0Ax%2B3%3D0+%5C%5C+%0A+x_%7B1%7D+%3D-3+%5C%5C+%0A+x%5E%7B2%7D+-3x%2B11%3D0+%5C%5C+%0AD%3C0)
действительных корней нет
Ответ:х=-3
30х + 3(х2-10х+25х) =0
30х + 3х2-30х+75х =0
3х2 + 75х =0
3х(х+25)=0
1) 3х=0
х=0
2) х+25 = 0
х =-25
1)
<span><span>-2sinxsin8x-2sinxsin2x=0
-2sinx(sin8x+sin2x)=-2sinx*2sin5xcos3x=0
sinx=0⇒x=πn
sin5x=0⇒5x=πn⇒x=πn/5
cos3x=0⇒3x=π/2+πn⇒x=π/6+πn/3
Ответ x=πn/5;x=π/6+πn/3
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2)
x-y=7
2x+y=8
прибавим
3x=15
x=5
y=5-7=-2
(5;-2)
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