Answer :
The lowest value of sinα is -1.
When x=1, you get:
[tex]f\left( x \right) =12-3\sin { \left( \frac { 3 }{ 2 } \pi \right) } \\ \\ =12-3\left( -1 \right) \\ \\ =12+3\\ \\ =15[/tex]
So the maximum value of the function is 15.
When x=1, you get:
[tex]f\left( x \right) =12-3\sin { \left( \frac { 3 }{ 2 } \pi \right) } \\ \\ =12-3\left( -1 \right) \\ \\ =12+3\\ \\ =15[/tex]
So the maximum value of the function is 15.