Final answer:
The function is increasing to the left of the critical point (-1, -7) and decreasing to the right. The end behavior of the function is approaching positive infinity as x approaches negative or positive infinity.
Step-by-step explanation:
To determine the intervals where the function y = 3x^2 + 6x - 4 is increasing or decreasing, we need to find the critical points by taking the derivative of the function. Taking the derivative of the function, we get y' = 6x + 6. Setting y' = 0 and solving for x, we find x = -1. This gives us the critical point of (-1, -7).
Since the coefficient of x^2 (3 in this case) is positive, the function opens upwards. Therefore, the function is increasing to the left of the critical point (-1, -7) and decreasing to the right of the critical point.
For the end behavior, as x approaches negative infinity, the function approaches positive infinity, and as x approaches positive infinity, the function approaches positive infinity as well.