F4 Quadratic Equations in one unknown

1) 對~ 但因為4-4(3)(2)<0, 所以無實根.
複數根
={2 ±√[4-4(3)(2)]}/ 2(3)
= 1/3(1±i√5) , i = √-1

2) x(x-2)+(x-3)(x-4) =122
x^2-2x+x^2-7x+12=122
2x^2-9x-110=0
x = {9 ±√[81-4(2)(-110)]}/ 2(2)
= 10 or -5.5

3) (2x-1)(5x+2)(2x-1)^2=0
(5x+2)(2x-1)^3=0
5x+2=0 or 2x-1=0
x=-2/5 or 1/2