一元二次方程

1. 4x2-4x+1=0
(2x-1) 2=0
2x-1=0x=1/2 2.5x2+4x-1=0
x=1/2 or x=-1
3.6x2+4(x+2)=9
6x2+4x+8=96x2+4x-1=0x=0.194 or x=-0.860
4.-2x2+3(4x-1)=5
-2x2+12x-3=5-2x2+12x-8=0x=0.764 or x=5.236
5.x2=3(x+6)
x2=3x+18x2-3x-18=0x=6 or x=-3 6.x2=4(2x-1)
x2=8x-4x2-8x+4=0
x=7.464 or x=0.536 7.6+4x-x2=0
x=-1.162 or x=5.162
8.x+3x2=13x2+x-1=0
x=0.434 or x=-0.768
9.2x2+x=7
2x2+x-7=0x=1.637 or x=-2.137
10.4x2-49=0
x2=49/4
x=-7/2 or x=7/2 11.x2-11x+28=0
x=7 or x=4
12.x2+18x+72=0
x=-6 or x=-12
13.x2-22x+121=0
x=11
14.3x2-10x+8=0
x=2 or x=4/3
15.6x2+5x-4=0
x=1/2 or x=-4/3
16.122+35x+8=0x=-1/4 or x=-8/3

17.49x2-42x+9=0
x=3/7
18.98x2-288=0
x2=144/49x=12/7 or x=-12/7
19.27x2-126x=0
x=14/3 or x=0
20.144-100x2=0
x=-6/5 or x=6/5
21.6-13x+2x2=0x=6 or x=1/2

VIc兄is just using calculator in some questions
I think we shoulad use the formula
x=(-(b)±√(b^2-4ac))/(2a)