-5.2x²=0
5.2x²=0
x²=0
x=0

19x²+14x-5=0
D = 14^2 - 419(-5) = 196 + 380 = 576
x1 = (-14 + √576)/(219) = (-14 + 24)/38 = 10/38 = 5/19
x2 = (-14 - √576)/(219) = (-14 - 24)/38 = -38/38 = -1

8x²+17x=0
x(8x+17) = 0
x = 0
8x+17 = 0
8x = -17
x = -17/8

x²-2x-3=0
(x-3)(x+1) = 0
x = 3 or x = -1

-9x²-15x-4=0
D = (-15)^2 - 4(-9)(-4) = 225 - 144 = 81
x1 = (-(-15) + √81)/(-18) = (15 + 9)/(-18) = 24/-18 = -4/3
x2 = (-(-15) - √81)/(-18) = (15 - 9)/(-18) = 6/-18 = -1/3

-35x²-33=0
-35x² = 33
x² = -33/35
x = ±√(-33/35) = ±i√(33/35)

x²+9x+10=0
(x+5)(x+2) = 0
x = -5 or x = -2

-13x²-11x-1=0
D = (-11)^2 - 4(-13)(-1) = 121 - 52 = 69
x1 = (-(-11) + √69)/(-26) = (11 + √69)/(-26)
x2 = (-(-11) - √69)/(-26) = (11 - √69)/(-26)