根号2是 1.4多 所以a=根号2-1
根号a的平方-2+a的平方分之1
=a-2+1/a
=根号2-1-2+1/(根号2-1)
=根号2-1-2+根号2+1
=2根号2-2
注意
/ 是分数线 分子/分母
1/(根号2-1)=(根号2+1)/[(根号2-1)(根号2+1)]
=(根号2+1)/1
=根号2+1
根号2是 1.4多 所以a=根号2-1
根号a的平方-2+a的平方分之1
=a-2+1/a
=根号2-1-2+1/(根号2-1)
=根号2-1-2+根号2+1
=2根号2-2
注意
/ 是分数线 分子/分母
1/(根号2-1)=(根号2+1)/[(根号2-1)(根号2+1)]
=(根号2+1)/1
=根号2+1