初2数学题目请教~！急~~

1.[x-2]^2=100

x-2=+/-10

x1=2+10=12
x2=2-10=-8

2.5x^2+2x=4

x^2+2/5x=4/5
[x+1/5]^2=21/25
x+1/5=+/-根21/5
x1=-1/5+根21/5
x2=-1/2-根21/5

3.[3x-4]^2+9x^2=16
[3x-4]^2+[3x+4][3x-4]=0
[3x-4][3x-4+3x+4]=0

[3x-4]*6x=0

x1=0
x2=4/3

4.4[x+2]^2=1-3[x+2]
4[x+2]^2+3[x+2]-1=0

[4(x+2)-1][(x+2)+1]=0

[4x+7][x+3]=0

x1=-7/4
x2=-3

1 x-2=10,x=8
3 (3x-4)^2=16-9x^2,(3x-4)^2=4^2-(3x)^2
(3x-4)(3x-4)=(4+3x)(4-3x)
(3x-4)(3x-4)=-(4+3x)(3x-4)
3x-4=-(4+3x)
4-3x=4+3x
x=0
4 把x+2看成一个整体
4（x+2）^2+3(x+2)-1=0
[(x+2)+1][4(x+2)-1]=0
(x+2)+1=0,4(x+2)-1=0
x=-3,x=-1

1.x-2=10或-10 =>x=12或-8
2.用公式 x=-b+根号(b^2-4ac) /2a x=-b-根号b^2-4ac /2a
3。展开 9x^2-24x+16+9x^2=16 =>x(3x-4)=0 x=0 x=4/3
4.展开 4x^2+19x+21=(4x+7)(x+3)=0 x=-3 x=-7/4

12