Me failing at another simple MC (1 Viewer)

[LoveHateSchool]

I fail at MC or Q15/Q16 level, I know it's bizarre.

I don't understand this function Q, probs haven't done it since year 11.

If f(x)=a^x + a^-x, then f^2(x)=

And answer is 2+f(2x)

 

[kenkap]

square the whole function you end up with a^2x + 2 + a^-2x

which is the same as 2 + f(2x) , since you are replacing x with 2x in the original function

 

[LoveHateSchool]

square the whole function you end up with a^2x + 2 + a^-2x

which is the same as 2 + f(2x) , since you are replacing x with 2x in the original function

Thank you! It's so simple <3 Muchly appreciated.