Trinômes carré parfait : $(a ,\pm b)^2 = a^2 ,\pm 2ab + b^2$

Go ! $(a - 3)^2 = a^2 - 2\cdot a\cdot 3 +3^2 = a^2 - 6a + 9 $ $(2a + 1)^2 = (2a)^2 + 2\cdot 2a\cdot 1 +1^2 = 4a^2 + 4a + 1 $ $(2a - 1)^2 = (2a)^2 - 2\cdot 2a\cdot 1 +1^2 = 4a^2 - 4a + 1 $

$( x+1)^2 =$	$\LARGE x^2+2x+1$
$2(1-x)^2 =$	$\LARGE2(1-2x+x^2)= 2x^2-4x+2$
$x(x^2+1)^2 =$	$\LARGE x(x^4+2x^2+1)= x^5+2x^3+x$
$(x+1)(x+1)^2 =$	$\LARGE(x+1)(x^2+2x+1)= x^3+3x^2+3x+1$