The standard form for this parabola is x = a(y-k)^2 + h because this is a sideways-opening parabola. Our h and k values for the vertex are (-4, -1). And it goes through (2,0). We just need to solve for the a. Filling in accordingly, 2 = a(0+1)^2-4 so 2 = a - 4. a = 6. A above.
3x+1