y^2 + 3y - 40 = 0
D=b^2 - 4 * a * c = 3^2 - 4 * 1 * (-40) = 9 + 160 = 169
y1= (-b - корень из D) / 2 * a = (-3 - 13) / 2 * 1 = -8
y2= (-b + корень из D) / 2 * a = (-3 + 13) / 2 * 1 = 5
y^2 + 3y - 40 = a * (y - y1) * (y - y2) = 1 * (y+8) * (y-5) = (y+8) * (y-5)
y^2 + 3y - 40 = 0
D=b^2 - 4 * a * c = 3^2 - 4 * 1 * (-40) = 9 + 160 = 169
y1= (-b - корень из D) / 2 * a = (-3 - 13) / 2 * 1 = -8
y2= (-b + корень из D) / 2 * a = (-3 + 13) / 2 * 1 = 5
y^2 + 3y - 40 = a * (y - y1) * (y - y2) = 1 * (y+8) * (y-5) = (y+8) * (y-5)