x的平方+x分之x的平方-1 因为x分之x的平方=x²/x=x所以原式化为
=x²+x-1
=x²+x+1/4-1/4-1
=(x²+x+1/4)-5/4
=(x+1/2)²-5/4
当x=2时
(2+1/2)²-5/4
=(5/2)²-5/4
=25/4-5/4
=20/4
=5