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ORAL DE MATHEMATIQUES 1

Pam Simonin

Created on March 20, 2026

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Transcript

oral de mathématiques

Start

PROBLéME N°8

Que vaut le produit suivant ?

( 1 + 1 ) ( 1 - 1 ) ( 1 + 1 ) ( 1 - 1 )….( 1 - 1 ) 2 3 4 5 999

On peut CALCULEr chaque facteur de la multiplication

* 1+ 1 = 2 + 1 = 3 2 2 2 2* 1- 1 = 3 - 1 = 23 3 3 3* 1+1 = 4 + 1 = 5 4 4 4 4 * 1- 1 = 5 - 1 = 4 5 5 5 5 * ..... * 1 - 1 = 999 - 1 = 998 999 999 999 999

Le produit devient : UNE MULTIPLICATION DE FRACTION

3 X 2 X 5 X 4 X...X 998 2 3 4 5 999

OBSERVATION

On remarque que l'on peut regrouper les facteurs 2 par 2. ( 3 x 2 ) ( 5 x 4 )... 2 3 4 5

On peut les simplifier 2 par 2 car chaque nombre du numérateur peut être simplifié avec le nombre du dénominateur de la fraction suivante.

5 x 4 4 5 = 1
3 x 2 2 3 = 1
chaque paire vaut 1....

Combien y a t il de paires ?

Les dénominateurs des facteurs vont de 2 à 999 il y a donc 999-2=997 intervales mais 997+1 = 998 fractions Le nombres de facteur est un chiffre paire donc on peut faire des groupes de 2

le produit final

peut s'ecrire

1 x 1 x 1 x 1 x ....x 1

CONCLUSION

produit total = 1

merci

Aylin - Adel - Mélina 3°7 Mars 2026

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Got an idea?

Let the communication flow!

With Genially templates, you can include visual resources to wow your audience. You can also highlight a particular sentence or piece of information so that it sticks in your audience’s minds, or even embed external content to surprise them: Whatever you like! Do you need more reasons to create dynamic content? No problem! 90% of the information we assimilate is received through sight and, what’s more, we retain 42% more information when the content moves.

  • Generate experiences with your content.
  • It’s got the Wow effect. Very Wow.
  • Make sure your audience remembers the message.