[Toán 11] Lượng giác

N

niemkieuloveahbu

[TEX]PT \Leftrightarrow x^2-2x+5=-4cos(a+b)\\\Leftrightarrow (x-1)^2+4=-4cos(ax+b)\\ \left{VT\geq 4\\VP\leq4\right.\\ PT\ co\ nghiem:\\ \left{x-1=0\\cos(ax+b)=-1\right.\\\Leftrightarrow \{x=1\\a+b=(2k+1)\pi,k\in Z[/TEX]
OK nhé
 
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