Réponse:
D(x) = 3²(5x+1)² - (x+1)²
D(x) = [3(5x+1]² - (x+1)²
D(x) = [3(5x+1)+(x+1)]×[3(5x+1)-(x+1)]
D(x) = (15x+3+x+1)(15x+3-x-1)
D(x) = (16x+4)(14x+2)
D(x) = (4×4x+4×1)(2×7x+2×1)
D(x) = 4(4x+1)×2(7x+1)
D(x) = 8(4x+1)(7x+1)
E(x) = 3²(x+1)² - 5²(x-1)²
E(x) = [3(x+1)]² - [5(x-1)]²
E(x) = (3x+3)² - (5x-5)²
E(x) = (3x+3+5x-5)(3x+3-5x+5)
E(x) = (8x-2)(-2x+8)
E(x) = (2×4x-2×1)(2×(-x)+2×4)
E(x) = 2(4x-1)×2(4-x)
E(x) = 4(4x-1)(4-x)