Answer:
(0.4, -57.9)
Step-by-step explanation:
y = 3x³ + 12x² - 10x - 56
dy/dx = 9x² + 24x - 10 = 0
x = [-24 +/- sqrt(24² - 4(9)(-10))]/(2×9)
x = -3.033006505, 0.3663398379
d²y/dx² = 18x + 24
For minima, d²y/dx² > 0 which is at x = 0.3663398379
y = 3(0.3663398379)³ + 12(0.3663398379)² - 10(0.3663398379) - 56
y = -57.90544608
