Question

I need to know how to do the answer and why that’s the anwer

Answer 1

Ok so the answer is
$4 {x}^{2}$

so we multiply numbers that have the same variable

$2 {x}^{3} \: \: \times {2x}^{ - 1}$
multiply 2 x 2

$2 \times 2 = 4$
then multiply the exponents

$x ^{3} \times x ^{ - 1}$
multipling like this will look like addition.
${x}^{3} \times {x}^{ - 1} = {x}^{2}$
so in other words you could do it like this too
${x}^{3} + {x}^{ - 1} = {x}^{2}$
now add the exponent with 4
$4 + {x}^{2} = 4x ^{2}$

now for the last part
${y}^{3} + {y}^{ - 3} = 0$
because -3 and 3 added together make 0
$0 + 4 {x}^{2} = 4 {x}^{2}$
I hope this help(it looks complicated but it's very easy and I hope I helped you out)