La fonction racine carrée notée $\sqrt{x}$ est la fonction réciproque de la fonction carrée notée $x²$.
Trouver la racine carrée d’un nombre, c’est comme si on se posait la question : « Quel nombre au carré donne ce résultat? »
Exemples
$\sqrt{\color{red}1} = \color{green}1$ car $\color{green}1\color{black}² = \color{green}1 \color{balck}\times \color{green}1 \color{black}= \color{red}1$
$\sqrt{\color{red}4} = \color{green}2$ car $\color{green}2\color{black}² = \color{green}2 \color{balck}\times \color{green}2 \color{black}= \color{red}4$
$\sqrt{\color{red}9} = \color{green}3$ car $\color{green}3\color{black}² = \color{green}3 \color{balck}\times \color{green}3 \color{black}= \color{red}9$
$\sqrt{\color{red}16} = \color{green}4$ car $\color{green}4\color{black}² = \color{green}4 \color{balck}\times \color{green}4 \color{black}= \color{red}16$
$\sqrt{\color{red}25} = \color{green}5$ car $\color{green}5\color{black}² = \color{green}5 \color{balck}\times \color{green}5 \color{black}= \color{red}25$
$\sqrt{\color{red}36} = \color{green}6$ car $\color{green}6\color{black}² = \color{green}6 \color{balck}\times \color{green}6 \color{black}= \color{red}36$
$\sqrt{\color{red}49} = \color{green}7$ car $\color{green}7\color{black}² = \color{green}7 \color{balck}\times \color{green}7 \color{black}= \color{red}49$
$\sqrt{\color{red}64} = \color{green}8$ car $\color{green}8\color{black}² = \color{green}8 \color{balck}\times \color{green}8 \color{black}= \color{red}64$
$\sqrt{\color{red}81} = \color{green}9$ car $\color{green}9\color{black}² = \color{green}9 \color{balck}\times \color{green}9 \color{black}= \color{red}81$
$\sqrt{\color{red}100} = \color{green}10$ car $\color{green}10\color{black}² = \color{green}10 \color{balck}\times \color{green}10 \color{black}= \color{red}100$
Racine carrée à la calculatrice
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