The graph of \(f\) on the interval \([0,5]\) is given below.
Using geometry, we can evaluate \(\int _0^5 f(x) \d x\) to find it equals \(\answer {6.5}\).
Again, using geometry, we can evaluate \(\int _1^4 f(x) \d x\) to find it equals \(\answer {4.5}\).
Finally, we can use geometry to find that \(\int _0^2 4f(x) \d x - \int _1^3 5f(x) \d x = \answer {-6.5}\).
The average value of \(f\) on \([0,5]\) is
The points \(c\) in \([0,5]\) where \(f(c) = \bar {f}\) are
Since \(1<\bar {f}<2\), the point \(c\) will be found only at the intervals where \(1<f(x)<2\).
By inspecting the graph of \(f\), we can see that the only such intervals are \((2,3)\) and \((4,5)\).
From the graph we can conclude that
\(f(x)=x-1\), for \(2<x<3\); and that
\(f(x)=6-x\), for \(4<x<5\).
Now we can solve the equation