Is $f(x)=x^2$ even or odd function?

Is $f(x)=x^2+1$ even or odd function?

These are functions symmetric on the $y$ axis.

Is $f(x)=x$  even or odd function?

Is $f(x)=\cos x$ even or odd function?

1131.   True or false : $f(x)=x^2$  is an even function.

Is the sentence true or false?

The sum of two even functions is even function.

Is the sentence true or false?

The product of two even functions is odd function.

True or false : The sum of two even functions is even function.

Is the sentence true or false?

Absolute value functions in the form $f(x)=a|x|+c$  is an even function.