You simply divide everything by x:
4x² : x = 4x (...as x ∙ 4 x = 4x²)
3x : x = 3 (...as x ∙ 3 = 3x)
10 : x = 10/x (...as x ∙ 10/x = 10)
x(4x + 3 + 10/x) → If you multiply everything in ( ) by x you will get 4x² + 3x + 10
4x² + 3x + 10 → If you divide everything in ( ) by ex you will get x(4x + 3 + 10/x)
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