Démontrer les égalités suivantes. a)22x² + 25x + 4 =(5x + 2)² - 3x² + 5x
b) (x + 5)(3x -2) + (x +5)(5x - 4 ) = (x + 5)(8x-6)
c) (5x + 8)² -4(2x + 5 )² = (3x - 6)(3x + 6)
Bonjour,
a)22x² + 25x + 4 = (5x + 2)² - 3x² + 5x =
22x² + 25x + 4 = 25x²+20x+4 - 3x² + 5x =
22x² + 25x + 4 = 22x² + 25x + 4
b) (x + 5)(3x -2) + (x +5)(5x - 4 ) = (x + 5)(8x-6)
(x + 5)(3x -2+5x - 4 ) = (x + 5)(8x-6)
(x + 5)(8x -6) = (x + 5)(8x-6)
c) (5x + 8)² -4(2x + 5 )² = (3x - 6)(3x + 6)
(5x+8+2(2x + 5 ))((5x+8-2(2x + 5 ))=
(5x+8+4x+10)(5x+8-4x-10) =
(9x+18)(x-2) =
3(3x+6)(x-2) =
(3x+6)(3x-6)*
a+
