Let $f : \mathbb{R} \to \mathbb{R}$ be defined by $f(x) = -6x^{2}$. Is $f$ a linear transformation?

1. $f(x+y) =$ .
   $f(x) + f(y) =$ $+$ .
   Does $f(x+y) = f(x) + f(y)$ for all $x,y \in \mathbb{R}$? choose Yes, they are equal No, they are not equal
   
   
2. $f(c x) =$ .
   $c(f(x)) =$ $\Big($ $\Big)$.
   Does $f(cx) = c(f(x))$ for all $c, x \in \mathbb{R}$? choose Yes, they are equal No, they are not equal
   
   
3. Is $f$ a linear transformation? choose f is a linear transformation f is not a linear transformation