Réponses

2013-03-30T13:48:08+01:00

Développer:

(4x+7) (2x-3) + (5x+2) (5x-2)

= 4x * 2x + 4x * (-3) + 7 * 2x + 7 * (-3) + 5x * 5x + 5x * (-2) + 2 *5x  + 2 * (-2)

= 8x² + 12x + 14x - 21 + 25x² - 10x + 10x - 4

= 33x²+ 26x - 25 

 

Développer et réduire:

(5x-7)² - (2x+3) (5x-7)

= (5x)² - 2 * 5x * 7 + 7² - ( 2x * 5x + 2x * (-7) + 3 * 5x + 3 * (-7) )

= 25x² - 70x + 49 - ( 10x² - 14x + 15x - 21)

= 25x² - 70x + 49 - 10x² + 14x - 15x + 21

= 15x² - 71x + 70