How many one-to-one functions are there from a set with two elements to a set with four elements?

  12

Step-by-step explanation:

There are 4×3 = 12 ways that two of the four elements can be mapped to the two elements of the smaller set. Here's a list of the 12 possible functions:

  {(a, 1), (b, 2}}, {(a, 2), (b, 1)}, {(a, 1), (b, 3)}, {(a, 3), (b, 1)},

  {(a, 1), (b, 4)}, {(a, 4), (b, 1)}, {(a, 2), (b, 3)}, {(a, 3), (b, 2)},

  {(a, 2), (b, 4)}, {(a, 4}, (b, 2)}, {(a, 3), (b, 4)}, {(a, 4), (b, 3)}

25

step-by-step explanation:

step-by-step explanation:

the shape,the size and the distance