Question

6. If X = {counting numbers until 7}, and Y = {2, 4, 6, 8 }. Find X – Y.
{7}
{8}
{1, 3, 5}
{1, 3, 5, 7}

Answer 1

Answer: Choice D)  {1, 3, 5, 7}

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Work Shown:

X = {counting numbers until 7}

X = {1,2,3,4,5,6,7}

Y = {2,4,6,8}

X - Y = {1, 3, 5, 7}

The basic idea with set subtraction is to start with the items in set X. Then erase anything you find in set Y (that's also in set X). So we'll erase 2,4,6 found in set X to be left with 1,3,5,7. We ignore the '8' since it's not found in set X.