Over which intereval is the graph of f(x)= -x^2+3x+8 increasing?

Answer:
It is increasing when x < 1
Step-by-step explanation:
If you substitute x = 1 in the equation you get that y = 10 at that point which is the maximum point at which graph reaches in the y direction. As you can see, the slope of the derivative is increasing, which means that the slope of the tangent line is increasing before that point.
Hope this helps