Need help with these matlab question.

10. Let v 1:20, write an expression that refers to only the elements that have odd-numbered subscripts in v. Your expression shall work correctly regardless of the length of any vector. Test your expression on vectors that have both an odd and even number of elements. 11. Create a 3 x 5 matrix of random integers, each in the inclusive range from 5 to 5. Get the sign of every element