(3x+2)(x-4)=0 5x^2+8x-4=0 25x^2-4=0 (x-2)^2-1=0 6x^2=18x , с решением, )

3x^2-10x-8=0
x1;2=[10+-sqrt(100+96)]/6
x1=23/6; x2=-1/2

5x^2+8x-4=0
x1;2=[-8+-sqrt(64+80)]/10
x1=2/5=0,4; x2=8/5=1,6

25x^2-4=0
x^2=0,16
x=sqrt(0,16)
x=+-0,4

(x-2)^2-1=0
x^2-4x+4-1=0
x^2-4x+3=0
x1;2=[4+-sqrt(16-12)]/2
x1=3; x2=1

6x^2=18x
6x^2-18x=0
6x(x-3)=0
x=0. x-3=0
x=3