ralph4 ralph4
  • 20-05-2016
  • Mathematics
contestada

Cos3x+cosx=2cos2xcosx

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GreenEyes71
GreenEyes71 GreenEyes71
  • 21-05-2016

[tex]cos(3x)+cos(x)=2\cdot cos\left(\dfrac{3x+x}{2}\right)\cdot cos\left(\dfrac{3x-x}{2}\right)=2\cdot cos(2x)\cdot cos(x).[/tex]

Green eyes.

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