用极限定义证明lim(x趋近于2)x^2=4

方法一lim(x-->2) (x^2 - 4) = lim(x-->2) (x 2)*(x-2)因为x 2和x-2在x-->2连续,所以lim(x-->2) (x 2)*(x-2) = lim(x-->2) (x 2)* lim(x-->2) (x-2) = (2 2)*(2-2) = 0所以lim(x-->2) (x^2 - 4) = 0即当x趋近于2时,x...