AIder MOI SVP LUI QUI TROUVE JLUI DONNE 20 POINT!!!

bonsoir

(2-5x)(4x+3) -(2-5x)²
8x+6-20x²-15x -(4-20x+25x²)
-20x²-7x+6 -25x²+20x-4
-45x² +13x +2

pourx = -1

-45(-1)² +13(-1) +2
-45 x1 -13+2
-45-13+2
-58+2
-56

51² =(50+1)² = 2500 +100 +1 = 2601

69 ² = (70 -1 )² =  4900 -140 +1 = 4761

23x17 = (20+3)(20-3) = 20²-3² = 400 -9 = 391

(x+3)² = x²+x+9

(2x-5)² = 4x²-20x+25

(7x+8)(7x-8) = 49x²-64