Bonjour,
x²+2x+1 = x²+2(x)(1)+1² = (x+1)²
x²-6x+9 = x²-2(x)(3)+3² = (x-3)²
x²-10x+25 = x²-2(x)(5)+5² = (x+5)²
x²+20x+100 = x²+2(x)(10)+10² = (x+10)²
4x²+4x+1 = (2x)²+2(2x)(1)+1² = (2x+1)²
49x²/16 - 36/121 = (7x/4)²-(6/11)² = (7x/4-6/11)(7x/4+6/11)
