ok so the answer is
[tex]4 {x}^{2} [/tex]
so we multiply numbers that have the same variable
[tex]2 {x}^{3} \: \: \times {2x}^{ - 1} \\ \\ [/tex]
multiply 2 x 2
[tex]2 \times 2 = 4[/tex]
then multiply the exponents
[tex]x ^{3} \times x ^{ - 1} [/tex]
multipling like this will look like addition.
[tex] {x}^{3} \times {x}^{ - 1} = {x}^{2} [/tex]
so in other words you could do it like this too
[tex] {x}^{3} + {x}^{ - 1} = {x}^{2} [/tex]
now add the exponent with 4
[tex]4 + {x}^{2} = 4x ^{2} [/tex]
now for the last part
[tex] {y}^{3} + {y}^{ - 3} = 0[/tex]
because -3 and 3 added together make 0
[tex]0 + 4 {x}^{2} = 4 {x}^{2} [/tex]
I hope this help(it looks complicated but it's very easy and I hope I helped you out)
