what are the equations

Looks like f(x) = -1- x²

               g(x) = sin(pi*x/2)

I am on a phone so can't see your pic nicely and not can understand what your questions real meaning but tho I'll do my bit to help u so equations are formed by expressions and they have two expressions on each side of the equal sign and those expressions r of the same value . An example of an equation is 

5 + 10 =10+5 

 Or 

x +10 = 10+5

in the above equation u could see that both the sides have the same value