`B=[(√x-2)/(x-1)-(√x+2)/(x+2√x+1)].(1-x)^2/2`
`⇔B=[((√x-2)(√x+1)-(√x+2)(√x-1))/((x-1)(√x+1))].(1-x)^2/2`
`⇔B=[(x-√x-2-(x+√x-2))/((x-1)(√x+1))].(1-x)^2/2`
`⇔B=[(-2√x)/((x-1)(√x+1))].(1-x)^2/2`
`⇔B=(√x(1-x))/(√x+1)`
`⇔B=(1-√x).√x`
`⇔B=√x-x`
`x=\sqrt(\sqrt(5)-\sqrt(3-\sqrt(29-12\sqrt(5))))`
`⇔x=\sqrt(\sqrt(5)-\sqrt(3-\sqrt((\sqrt(20)-3)^2)))`
`⇔x=\sqrt(\sqrt(5)-\sqrt(3-\sqrt(20)-3))`
`⇔x=\sqrt(\sqrt(5)-\sqrt((\sqrt(5)-1)^2))`
`⇔x=\sqrt(\sqrt(5)-\sqrt(5)+1)`
`⇔x=1`
`⇒B=1-1=0`
`B>0`
`-\sqrt(x)(\sqrt(x)-1)>0`
`⇔\sqrt(x)(\sqrt(x)-1)<0`
`⇔\sqrt(x)-1<0`
`⇔\sqrt(x)<1`
`⇔0<x<1`
`B=√x-x`
`⇔B=-(x-√x+1/4)+1/4`
`⇔B=-(√x-1/2)^2+1/4≤1/4`
`''=''`khi :
`√x-1/2=0`
`⇔x=1/4`
