document.write( "Question 1173445: the midpoint of AB is M (3,-2) if the coordinates of A are (1,-3), what are the coordinates of B?
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Algebra.Com's Answer #798662 by greenestamps(13200)\"\" \"About 
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\n" ); document.write( "Using formal algebra....

\n" ); document.write( "The x and y coordinates of the midpoint are the averages of the x and y coordinates of the two endpoints.

\n" ); document.write( "A(1,-3)
\n" ); document.write( "M(3,-2)
\n" ); document.write( "B(m,n)

\n" ); document.write( "(m+1)/2 = 3 --> m+1 = 6 --> m = 5

\n" ); document.write( "(n-3)/2 = -2 --> n-3 = -4 --> n = -1

\n" ); document.write( "ANSWER: B(5,-1)

\n" ); document.write( "You should understand how that process gives you the answer; and you should know how to solve the problem by that method.

\n" ); document.write( "But if solving without formal algebra is allowed, an informal solution is much faster and easier:

\n" ); document.write( "From A(1,-3) to the midpoint M(3,-2) is 2 units to the right and 1 unit up; from the midpoint M(3,-2) to the other endpoint B is again 2 units to the right and 1 unit up:

\n" ); document.write( "B is (3+2,-2+1) = (5,-1).
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