B=(2-x)² A=(1-x)² B-A=(2-x)²-(1-x)² ((B-A=((2-x)+(1-x))((2-x)-(1-x (B-A=(2-x+1-x)(2-x-1+x (B-A=(3-2x)(1 B-A=3-2x x-1)²< ²(x-2)