1、x1=3 x2=-9
2、x²+2mx+m²-m²-3m²=0
( x+m)²-2²m²=0
(x-m)(x+3m)=0
x1=m x2=-3m
3、 x²+18x-243=0
x²+2×9x+9²-9²-243=0
( x+9)²-18²=0
(x-9)(x+27)=0
x1=9 x2=-27
1、x1=3 x2=-9
2、x²+2mx+m²-m²-3m²=0
( x+m)²-2²m²=0
(x-m)(x+3m)=0
x1=m x2=-3m
3、 x²+18x-243=0
x²+2×9x+9²-9²-243=0
( x+9)²-18²=0
(x-9)(x+27)=0
x1=9 x2=-27