Q. Find the area under the graph of f over the interval [−2,4].f(x)={x2+65xx≤2x>2
Identify Intervals and Functions: Identify the intervals and corresponding functions for the piecewise function f(x). The function f(x) is defined as x2+6 for x≤2, and as 5x for x > 2. We need to find the area under the graph of f(x) from x=−2 to x=4. This means we will have to split the integral at x=2, where the definition of the function changes.
Set Up Integral for First Interval: Set up the integral for the first interval from x=−2 to x=2. For x≤2, f(x)=x2+6. We will integrate this function from −2 to 2. The integral is ∫−22(x2+6)dx.
Calculate Integral for First Interval: Calculate the integral for the first interval. ∫−22(x2+6)dx=[3x3+6x]−22. Evaluating this from −2 to 2 gives: (323+6⋅2)−(3(−2)3+6⋅(−2)).
Perform Calculations for First Interval: Perform the calculations for the first interval.(23/3+6⋅2)−((−2)3/3+6⋅(−2))=(8/3+12)−(−8/3−12).Simplify the expression: (8/3+12+8/3+12)=(16/3+24)=(16/3+72/3)=88/3.
Set Up Integral for Second Interval: Set up the integral for the second interval from x=2 to x=4. For x > 2, f(x)=5x. We will integrate this function from 2 to 4. The integral is ∫245xdx.
Calculate Integral for Second Interval: Calculate the integral for the second interval.∫245xdx=[25x2]24.Evaluating this from 2 to 4 gives: (25⋅42)−(25⋅22).
Perform Calculations for Second Interval: Perform the calculations for the second interval.(5×42/2)−(5×22/2)=(5×16/2)−(5×4/2)=(40)−(10)=30.
Add Areas for Total Area: Add the areas from both intervals to find the total area under the graph of f(x) from x=−2 to x=4. Total area = Area from first interval + Area from second interval. Total area = 388+30.
Convert Second Area and Add: Convert the second area to a fraction with a common denominator and add the two areas.Total area = 388+(30×33)=388+390=3178.
Convert Total Area: Convert the total area to a mixed number or decimal if necessary.Total area = 3178=5931.
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