x^2 +2x - 63 = 0
D = 4 -4(-63) = 4 + 252 = 256; YD = 16
x1 = (-2 + 16)/ 2 = 7
x2 = (-2 -16)/2 = - 9
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0,9x - 3x ^2 = 0
x (0,9 - 3x) = 0
x1 = 0
x2 = 0,3
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2x^2 -5x + 2 = 0
D = 25 - 4(2)(2) = 25 - 16 = 9; YD = 3
x1 = ( 5 + 3)/4 = 2
x2 = (5 - 3)/4 = 2/4 = 0,5
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x^2 - 2x - 8 = 0
D = 4 - 4(-8) = 4 + 32 = 36; YD = 6
x1 = (2 + 6)/2 = 4
x2 = (2 - 6)/2 = - 2