Question

I need to find x of the quadratic function y=-5/3x^2-x-4. I'm supposed to use the formula x=-b/2a. The negative sign only applies to b. A=-5/3 and B=-1. When I substitute these values in I get -(-1)/2(-5/3). After working this out I get 1 over -10 over 3(1)/(-10/3). after simplifying I get -3/10. Next I put -3/10 in the x values of the function so it looks like this- y=-5/3(-3/10)^2-(-3/10)-4. The answer I get is -77/20. Did I do this problem right?

Answer 1

x = -b/2a will enable you to find the vertex of the parabola.

x = -3/10 is correct
y = -7720 is correct.

So, the vertex of the parabola is at (-3/10,-7720)

I hope that is what you were after!