Réponses

2014-10-05T17:35:31+02:00
(5x+7)²=25x²+70x+49

(9x-4)²=81x²-72x+16

(5x-7)²+(9x-4)²=25x²-70x+49+81x²-72x+16=106x²-142x+65

(5x-7)²-(9x-4)²=25x²-70x+49-81x²+72x-16=-56x²+2x+33

  • Utilisateur Brainly
2014-10-05T19:00:35+02:00
(5x + 7)²
= 25x² + 70x + 49

(9x - 4)²
= 81x² - 72x + 16

(5x - 7)² + (9x - 4)²
= 25x² - 70x + 49 + 81x² - 72x + 16
= 106x² - 142x + 65

(5x - 7)² - (9x - 4)²
= 25x² - 70x + 49 - 81x² + 72x - 16
= - 56x² + 2x + 33