Ответы и объяснения

2013-05-12T18:43:29+04:00

2(x^2-40)= -x^2+6(x+4)+1

2x^2 - 80 = -x^2 + 6x + 24 + 1

2x^2 - 80 = -x^2 + 6x + 25

2x^2 + x^2 - 6x = 25 + 80

3x^2 - 6x = 105

3x^2 - 6x - 105 = 0

D = b^2 - 4ac = (-6)^2 - 4*3*(-105) = 36 + 1260 = 1296

VD = V1296 = 36

x1 = (6+36)/2*3 = 42/6 = 7

x2 = (6-36)/2*3 = -30/6 = - 5