1、m != 0且|m-2| = 2,得m = 4
2、非零a,b,c满足a+b+c = 0 得 c/a -(-b/a) +1 = 0即x1x2 - x1 - x2 +1 =0 得(x1-1)(x2-1) = 0,则必有一根为1
3、4m^2+2m+1 = 2(2m^2+m-2) +5 = 11
4、若a为实数则是
5、a-2 != 0,|a|-2 = 0得a= -2
6、方程解x=1或2,a^2+2/a = 3或5
7、2x+1/1-x=4解为1/2,代入得k=3
8、±1/2 ,±2/3
9、x^2 + x = 0；x^2 + 7x = 0
10、x^2 = 9 ,x = ±3；x^2 = 50,x= ±5√2
11、x-x^2 = x-1 得 x=±1
12、?
13、原式=x^2+6x+9+m^2 -9 =(x+3)^2 +m^2-9,则m^2-9=0,m=±3
14、4x^2 = 25, x =5/2 (-5/2舍)
15、[x-(2+√3)][x-(2-√3)]=0,即x^2-4x+1 = 0
16、同理4y^2±12y+9 =(2y±3)^2,得m=±12
17、x^2-2x+1=3, (x-1)^2 =3, x=1±√3；x^2+4x+4=5, (x+2)^2 =5, x=-2±√5
18、原式=x^2-4x+4+7=(x-2)^2+7,因为x为实数,所以(x-2)^2恒大于等于零,所以x^2-4x+11恒大于零