document.write( "Question 1091985: (x+1)^2-(y-1)^2=20, x^2-(y+2)^2= 24 \n" ); document.write( "
Algebra.Com's Answer #706521 by greenestamps(13203)\"\" \"About 
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\n" ); document.write( "Step 1: If you expand everything in both equations, then you will have an x^2 and y^2 term in both equations; so when you compare the two equations by subtraction, the squared terms will cancel out, leaving you with a linear equation in x and y.

\n" ); document.write( "Step 2: You can solve that linear equation for one of the variables and substitute into either of the original equations to solve for one variable; since you will be solving a quadratic equation, there will probably be two solutions.

\n" ); document.write( "Step 3: substituting each of those values into one of the original equations will give you the corresponding values of the other variable.

\n" ); document.write( "

\n" ); document.write( "Step 1: Get a linear equation from the two given equations by expanding, then subtracting one equation from the other...

\n" ); document.write( "\"%28x%5E2%2B2x%2B1%29-%28y%5E2-2y%2B1%29+=+20\"
\n" ); document.write( "\"x%5E2%2B2x-y%5E2%2B2y+=+20\" (1)

\n" ); document.write( "\"x%5E2+-+%28y%5E2%2B4y%2B4%29+=+24\"
\n" ); document.write( "\"x%5E2-y%5E2-4y-4+=+24\"
\n" ); document.write( "\"x%5E2-y%5E2-4y+=+28\" (2)

\n" ); document.write( "\"2x%2B6y+=+-8\" (by subtracting (2) from (1))
\n" ); document.write( "\"x%2B3y+=+-4\" (3)

\n" ); document.write( "Step 2: Solve (3) for x and substitute in the second original equation; solve the resulting quadratic equation for two values of y.

\n" ); document.write( "\"x+=+-3y-4\" (4)
\n" ); document.write( "\"%28-3y-4%29%5E2+-+%28y%2B2%29%5E2+=+24\"
\n" ); document.write( "\"9y%5E2%2B24y%2B16-y%5E2-4y-4+=+24\"
\n" ); document.write( "\"8y%5E2%2B20y-12+=+0\"
\n" ); document.write( "\"2y%5E2%2B5y-3+=+0\"
\n" ); document.write( "\"%282y-1%29%28y%2B3%29+=+0\"

\n" ); document.write( "The two values for y are 1/2 and -3.

\n" ); document.write( "Step 3: Find the corresponding x value for each y value, using (4).

\n" ); document.write( "\"x+=+-3%281%2F2%29-4+=+-11%2F2\"
\n" ); document.write( "\"x+=+-3%28-3%29-4+=+5\"

\n" ); document.write( "The points of intersection of the two graphs (the pair of (x,y) values that satisfy both equations) are (-11/2,1/2) and (5,-3).
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