Mathématiques

Question

développer : C = ( 2x + 1) ( x - 7 )
D = - 5( x - 2 ) + ( x - 8 ) + 2 ( x - 1 )

détailler : A = 2 + ( 3 - 7 ) x ( 6 - 2 )
B = - 4 / ( - 2 ) + ( - 5 - 2 )

merci d'avance !

2 Réponse

  • C= 2x² - 14x + x - 7
    C= 2x²- 13x-7

    D= -5x +10+x-8+2x-2
    D=-2x 



  • Bonsoir,

    C = ( 2x + 1 ) ( x - 7 )
    = 2x * x + 2x * ( - 7 ) + 1 * x + 1 * ( - 7 )
    = 2x² - 14x + x - 7
    = 2x² - 13x - 7

    D = - 5 ( x - 2 ) + ( x - 8 ) + 2 ( x - 1 )
    = - 5 * x - 5 * ( - 2 ) + x - 8 + 2  *x + 2 * ( - 1 )
    = - 5x + 10 + x - 8 + 2x - 2
    = -2x

    A = 2 + ( 3 - 7 ) x ( 6 - 2 )
    = 2 + - 4 x 4
    = 2 - 16
    = - 14

    B = - 4 / ( - 2 ) + ( - 5 - 2 )
    = 2 - 7
    = - 5

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