I want to shade the area between the formula

eqn=(a (Sqrt[a] (-40 + 37 a + 10 a^2 - 3 a^3) + (-1 + a)^2 (32 +
a) ArcTanh[Sqrt[a]]))/(2 (-Sqrt[a] (1 + a) + (-1 + a)^2 ArcTanh[
Sqrt[a]]))


and -3/2.

To be clearer: -3/2 < region to be shaded < eqn

I tried with:

Show[{{Plot[{eqn, -3/2}, {a, -2, 1.5}]},
Plot[{eqn, -3/2}, {a, -1.2, 1},
Filling -> {1 -> {-3/2, Automatic}}]}, PlotRange -> {-2, 4}]


but I don't get what I want: it shades also

eqn < region < -3/2


Any ideas?

I am sorry but I don't understand how to link a figures, I hope I explained myself...

Oh, I am using Mathematica 8.

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Check the documentation for Filling - you can specify different filling styles for above and below the curve. –  Simon Woods Dec 1 '13 at 14:25

You can use

Plot[{eqn, -3/2}, {a, -1.2, 1}, Filling -> {1 -> {-3/2, {White, LightBlue}}}, PlotRange -> {-2, 4}]


to fill the area between the two curves: >-3/2=LightBlue and <-3/2=White

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It worked. thank you –  mattiav27 Dec 1 '13 at 15:59