Comments by "Fhf Fhf" (@fhffhff) on "Светлана Лада-Русь" channel.

  1. y'/√(y²+4)=±√-1 ln|y+√(y²+4)|=±√-1x+c y+√(y²+4)=(sinx+c1cosx)c, {-2/(sinx+co sxc1)/c+0,5(sinx +c1cosx)c=y,(sinx+c1 cosx)c≥y;y=-2/(sinx+cosxc1)/c+0,5(sinx +c1cosx)c sin(x+arccos(1/√(1+c1²)))c>0
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  2. а,a+1,b a-1,a-2 2a-3,4+b a=0,5b+2 b-a-1=4 0,5b=7,b=14,a=9.
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  3. $(e^x-1)/xdx=En=1;∞x^n/n!/n+c
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  4. y"+4y=5e^-x k²+4=0 k=±2i y0=c1sin2x+c2 cos2x y=c3e^-x c3e^-x+4c3e^-x=5e^-x,c3= 1 yp=e^-x y=c1sin2x+c2cos2x+e^-x
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  5. (x-6)²+(y+1)²=64 O(6;-1),R=8 C=16π
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  6. х=2(у-0,25)²+4,875,х≥4,875 F(5;0) x=4,75
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  7. (3x-8)/(x-2)-(x-2)/(x+2)=(2x²-6x+44)/(x²-4) (8x-64)/(x-2)/(x+2)=0,x=8;≠±2
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  8. 645/8000=0,080625
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  9. (x-8)(x+8)/(x-4)/(x²+4x+16):((x+8)²/4/(x²+4x+16)=4(x-8)/(x+8)/(x-4)
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