1
(m+3)*m² - (m² - 1)*m + 4*(2 - 2m²) = m³ + 3m² - m³ + m + 8 - 8m² = -5m² + m + 8
3
9x + 8x² = -1
8x² + 9x + 1 = 0
D=81 - 32 = 49 = 7²
x12=(-9+-7)/16 = -1 -1/8
4
(x-2)/(2x-6) - (x-1)/(3x-9) = (x-2)/2(x-3) - (x-1)/3(x-3) = [3(x-2) - 2(x-1)]/6(x-3) = (3x - 6 - 2x + 2) / 6(x-3) = (x-4)/6(x-3)
2
(x+4)/(xy-x²) + (y+4)/(xy-y²) = (x+4)/x(y-x) + (y+4)/y(x-y) = [(x+4)*y - (y+4))*x]/(xy(y-x)) = (xy + 4y - xy - 4x) / (xy(y-x) = 4(y-x)/(xy(y-x) = 4/xy