3. (3x² + 7x - 6)/(4 - 9x²) = (3x - 2)(x + 3)/(2 - 3x)(2 + 3x) = - (x +3)/(2 +3x)
3x² + 7x - 6 = 0
D = 7² + 4·3·6 = 121 = 11²
x₁ = 2/3, x₂ = - 3
3x² + 7x - 6 = 3(x - 2/3)(x+3) = (3x - 2)(x+3) = - (2 - 3x)(x+3)
4. По теореме Виета х₁ + х₂ = - р, х₁х₂= q
12 + x₂= 26, x₂= 26 - 12 = 14
q = 12·14= 168
x² - 26x + 168 = 0