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Løs ligningen:

2 cos^2 x + [symbol:rot] (2) cos x - 2 = 0, der x (- [0.2 [symbol:pi] ]

tosken wrote:Løs ligningen:

2 cos^2 x + [symbol:rot] (2) cos x - 2 = 0, der x (- [0.2 [symbol:pi] ]

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2. gradslikning mhp cos(x):

[tex]cos(x)\;=\;[/tex][tex]-sqrt{2}\pm sqrt{2+16}\over 4[/tex]

[tex]cos(x)\;=\;[/tex][tex]-sqrt{2}\pm 3sqrt{2}\over 4[/tex]

cos(x) > 0

cos(x) = [tex]\;sqrt2\over 2[/tex]

x = arc cos( [symbol:rot] (2) / 2) + k2 [symbol:pi]

x = [tex]\pm {\pi \over 4}[/tex][tex]+k\cdot 2\pi[/tex]

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