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5.2 Assumptions • 167> is(x, real);trueIn this next example, Maple still assumes that the variable a is negative.> eq := xi^2 = a;eq := ξ 2 = a~> solve( eq, {xi} );{ξ = √ −a~ I}, {ξ = −I √ −a~}To remove assumptions that you make on a name, simply unassignthe name. However, the expression eq still refers to a~.> eq;ξ 2 = a~You must remove the assumption on a inside eq before you removethe assumption on a. First, remove the assumptions on a inside eq.> eq := subs( a=’a’, eq );eq := ξ 2 = aThen, unassign a.> a := ’a’;a := aFor more information on the assume facility, refer to ?assume.If you require an assumption to hold for only one evaluation, then youcan use the assuming command, described in the following subsection.When using the assuming command, you do not need to remove theassumptions on unknowns and equations.