Answer:
(a) 12
Step-by-step explanation:
The integral over the reverse range is the opposite of the integral over the forward range. The integral over adjoining ranges is the integral over the whole range.
Application
[tex]\displaystyle \int_{-1}^5{f(x)}\,dx=\int_{-1}^1{f(x)}\,dx+\int_{1}^5{f(x)}\,dx\\\\=\int_{-1}^1{f(x)}\,dx-\int_{5}^1{f(x)}\,dx=5-1=4[/tex]
Then 3 times the integral is ...
[tex]\displaystyle 3\int_{-1}^5{f(x)}\,dx=3(4)=\boxed{12}[/tex]
