<span>2x-(x+1)^2=3x^2-5
2х-x^2-2x-1=3x^2-5
-x^2-1=3x^2-5
-4x^2=-4
x^2=1
x=-+1</span>
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Ответ-------------------------
Arccos(x)`=-1/(√(1-x²)
arccos²(x)`=-2*arccos(x)/√(1-x²)
1/arccos²(x)=(1`*arccos²(x)-1*arccos²(x)`)/arccos⁴(x)=
=(0-(-2*arccos(x)/√(1-x²))/arccos⁴(x)=2*arccos(x)/(arccos⁴(x)*√(1-x²)).