3 ( x + 2 )² = 1/3( x + 2 )²=1/9x + 2=±1/3x=-2±1/3∴ x1=-7/2 x2=-5/2x² + 2 x = 9999 x² + 2 x +1=10000（x+2）²=10000x=-2±100∴x1=98 x2=-102