can someone please help me find the inverse of f(x) = -3x + 21. and determine whether the inverse is a function, and state its domain and range.

Question

anonymous · Answer

$$a)f^{-1} (x)=-\frac{ 1 }{ 3 }x+7$$
         ^not a function^
$$b)f^{-1} (x)=\frac{ -x+7 }{ 3 }$$
         ^not a function^
$$c)f^{-1} (x)=-\frac{ 1 }{ 3 }x+7$$
         ^^function; D: all real numbers; R: all real numbers.^^
$$d)f^{-1} (x)=\frac{ -x+7 }{ 3 }$$
         ^^function; D: all real numbers; R: all real numbers.^^