f (x) = (x^2 + 4)(x^2 + 8x + 25). Find the roots of f (x) = 0

firstly, x² + 4 = 0 x² = -4 x = 2i x = -2iSecondly, x² + 8x + 25 = 0 using the quadratic formulae: x = (-b +- sqrt(b² - 4ac))/2a x = (-8+-sqrt(64-100))/2 x = -8/2 +- sqrt(-36)/2 x = -4 + 3i x = -4 - 3i