Answer:
7
Step-by-step explanation:
1. Approach
The average rate of change can simply be defined as the slope of a line that passes through any two points on a coordinate plane. In this situation, one is given a function, and one is asked to find the rate of change over an interval.
Given function: [tex]f(x)=x^2+3x[/tex]
Intervale, [tex][0, 4][/tex]
This can be done by evaluating the endpoints of the interval by substituting them into the function. Then writing the resulting the form of a point on the coordinate plane ([tex]x, y[/tex]). Finally, one can find the slope of the line that passes through the points by using the following slope formula,
[tex]\frac{y_2-y_1}{x_2-x_1}[/tex]
Where ([tex]x_1,y_1[/tex]) and ([tex]x_2,y_2[/tex]) are coordinate points.
2. Find the points
With the function (f(x)), substitute the end points of the itnerval ( [0, 4] ) into the function to generate coordinate points,
[tex]f(x)=x^2+3x[/tex]
[ 0, 4 ]
[tex]f(0)=(0)^2+3(0)\\=0 + 0\\ =0[/tex]
Point: (0, 0)
[tex]f(4)=(4)^2+3(4)\\= 16 + 12\\ = 28[/tex]
Point: (4, 28)
3. Find the average rate of change,
Now substitute the points the formula to find the slope, then simplify to evaluate
[tex]\frac{y_2-y_1}{x_2-x_1}[/tex]
(0, 0), (4, 28)
Substitute,
[tex]\frac{y_2-y_1}{x_2-x_1}\\\\=\frac{28-0}{4-0}\\\\=\frac{28}{4}\\\\= 7[/tex]
The average rate of change is 7.
