Melody

Because you can work all the others out from thosw ones.

y=x^2 is a concave up parabola with vertex at (0,0)

y=-x^2 is its reflection in the x axis.  That is it is a concave down parabola with vertex at (0,0)

See if this helps

y=(x-1)(x-2)(x-(3/5))

y=a(x-1)(x-2)(5x-3)     where 'a' is a constant

That is really neat Heureka, thank you 

Sasini, any normal number raised to the power of zero is 1  

Thanks Mikado, perhaps you should give some instruction on how to do it by hand. :)

I like that one.  Thanks awsomenes 

subtract 2/3 from both sides

then

multiply both sides by -5

They all go into 36 so it is 36