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geometry senior
Problem
The vertices of a quadrilateral lie on the graph of , and the -coordinates of these vertices are consecutive positive integers. The area of the quadrilateral is . What is the -coordinate of the leftmost vertex?
(A)
(B)
(C)
(D)
Solution
Let the coordinates of the quadrilateral be . We have by shoelace's theorem, that the area is We know that the numerator must have a factor of , so given the answer choices, is either or . If , the expression does not evaluate to , but if , the expression evaluates to . Hence, our answer is .
Final answer
D