Given that function f : R → R defined by f(x) = 6^x + 6^|x|

Let f(x) = f(y)

⇒ 6^x + 6^|x|=6^y + 6^|y|

Only when x = y

So, f is one-one.

Now for y=f(x)

y can never be negative which means for no x ϵ R y is negative.

So, f is not onto but into.