None of those show another way to 64
6*6*6*6=1296
4*4*4*4*4*4=4096
6+6+6+6=24
6*4=24
Another way to show 64 is 8*8 or 4^3
Sin squared x equals 3 cos squared x
I am unsure about the very last problem but I can help with the first two
1) (y+1)+4
If we combine the numbers 1 and 4, we get +5 and can isolate the numbers from the variable.
This would give us

2) (6*r)*7
remember that we do not have to explicitly state 6*r
Instead, we can write it as 6r
this helps us get rid of the parentheses
now we can write it as

I hope this helps!:)