Question

Fie aA multimea solutilor ale ecuatie x²+x-6=0 Determinati (A\N)​

Answer 1

 

$\displaystyle\\x^2+x-6=0\\\\x_{12}=\frac{-b\pm\sqrt{b^2-4ac}}{2a}=\frac{-1\pm\sqrt{1+24}}{2}=\frac{-1\pm5}{2}\\\\x_1=\frac{-1-5}{2}=\frac{-6}{2}\\\\\boxed{\bf x_1=-3}\\\\x_2=\frac{-1+5}{2}=\frac{4}{2}\\\\\boxed{\bf x_2=2}\\\\\boxed{\bf A=\{-3;~2\}}\\\\\boxed{\bf A\backslash N=\{-3\}}\\\\\boxed{\text{\bf card}(\bf A\backslash N)=1}$

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