Answer:
x > -3
[tex]\sf (-3, \infty)[/tex]
Step-by-step explanation:
Domain: input values (x-values)
Monotonic increasing: always increasing.
A function is increasing when its graph rises from left to right.
The graph of a quadratic function is a parabola. If the leading term is positive, the parabola opens upwards. The domain over which the function is increasing for a parabola that opens upwards is values greater than the x-value of the vertex.
Vertex
Standard form of quadratic equation: [tex]\sf y=ax^2+bx+c[/tex]
[tex]\textsf{x-value of vertex}=\sf -\dfrac{b}{2a}[/tex]
Given function:
[tex]\sf y=x^2+6x[/tex]
Therefore, x-value of function's vertex:
[tex]\sf \implies x= -\dfrac{6}{2}=-3[/tex]
Final Solution
The function is increasing when x > -3
[tex]\sf (-3, \infty)[/tex]
