Question 1167228
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The map    x ---> 2x^3+1    from integer numbers to integer numbers is injective,  but is not bijective.



In other words,  the image of this map does not cover the entire set of integer numbers.



For example,  the number  11  does not belong to the image,  since the equation


                2x^3 + 1 = 11


has no solution in integer numbers (due to obvious reasons).