1.若x+ y=6,xy=4,且x>y,则代数式√x-√y / √x +√y的值为_________.
2.若x=1/√2+1,则代数式x^2+2x+1的值为__________.
1.若x+ y=6,xy=4,且x>y,则代数式√x-√y / √x +√y的值为_________.
2.若x=1/√2+1,则代数式x^2+2x+1的值为__________.
x+y+2√xy=(√x +√y)^2=6+2*2=10 x+y-2√xy=(√x -√y)^2=6-4=2 √x-√y / √x +√y=2/10=1/5
2. x=1/√2+1分子分母同乘以√2-1得x=√2-1 x^2+2x+1=(x+1)^2=(√2-1 +1)^2=2