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Test-Lidia
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<p> </p> <div align="center"> <table style="color: #003300; border: 4px solid #003300; float: none; text-align: left; vertical-align: top; width: 400px; background-image: none; background-color: #ffffcc;" border="4" frame="void" rules="none"> <tbody> <tr align="center"> <td style="background-color: #003300; background-image: none; color: #ffcc00; text-align: center; vertical-align: top; border-style: none;" valign="top" width="NaNpx"><span style="color: #ffff99; font-size: large;">Equacions biquadrades</span></td> </tr> <tr> <td valign="top" width="NaNpx"><span style="font-size: small;"><strong>Per resoldre equacions del tipus:</strong></span><br /><span style="font-size: small;"><strong>a·(x<sup>n</sup>)<sup>2</sup> + b(x<sup>n</sup>) + c = 0</strong></span><br /><span style="font-size: small;"><strong>es fa el canvi de variable t = x<sup>n</sup>, es troben les solucions de at<sup>2</sup> + bt + c = 0, i se'n dedueixen les solucions en x.</strong> </span><br /><br /><span style="color: #000000; font-size: small;"><em>Exemple:<br />2x<sup>4</sup> -20x<sup>2</sup> + 18 = 0, si t=x<sup>2</sup>, s'escriu: 2t<sup>2</sup>-20t+18=0.<br />El discriminant és 256, i les solucions: t = 1 i t = 9.<br />Com que t és x<sup>2</sup>, les solucions són x = ±1 i y = ±3</em></span></td> </tr> </tbody> </table> </div>
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Thursday, 23 August 2018, 11:09 AM
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