Answer and Step-by-step explanation:
Obviously addition is closed for R including both infinities
As t+infty = infty +t = infty and t+(-infty) =(-infty)+t =(-infty)
and inverse are -infty for infty and infty for -infty
Hence a group under addition
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But regarding multiplication
we can say 1/infty = 2/infty =0
Hence infinity*0 is not unique.
Also infinity and -infty do not have multiplicative inverse as there is no t such that t*infty = 1
Hence cannot be a vector space.