document.write( "Question 1180555: Greetings,
\n" ); document.write( "I am having troubles solving this question and confused on how to start: If f (x1, x2) = a + bx1 + cx2 + dx1x2, what is f (x1 + k, x2) - f (x1, x2)?
\n" ); document.write( "Do i just plug in x1 + k every time I see x1 for the first part?
\n" ); document.write( "If you could provide the solution and a brief explanation thank you! \n" ); document.write( "
Algebra.Com's Answer #810273 by math_tutor2020(3817)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "Yes you are correct. You'll replace every x1 with x1+k to find that,
\n" ); document.write( "f(x1, x2) = a + b*x1 + c*x2 + d*x1*x2
\n" ); document.write( "f(x1+k, x2) = a + b*(x1+k) + c*x2 + d*(x1+k)*x2
\n" ); document.write( "f(x1+k, x2) = a + b*x1+b*k + c*x2 + d*x1*x2+d*k*x2\r
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\n" ); document.write( "\n" ); document.write( "Then we subtract off f(x1,x2) from both sides
\n" ); document.write( "You should find that the following terms cancel
  • a and -a
  • b*x1 and -b*x1
  • c*x2 and -c*x2
  • d*x1*x2 and -d*x1*x2
In short, everything of f(x1, x2) = a + b*x1 + c*x2 + d*x1*x2 cancels out due to subtraction\r
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\n" ); document.write( "\n" ); document.write( "So,
\n" ); document.write( "f(x1+k, x2) - f(x1,x2) = a + b*x1+b*k + c*x2 + d*x1*x2+d*k*x2 - f(x1,x2)
\n" ); document.write( "f(x1+k, x2) - f(x1,x2) = a + b*x1+b*k + c*x2 + d*x1*x2+d*k*x2 - (a + b*x1 + c*x2 + d*x1*x2)
\n" ); document.write( "f(x1+k, x2) - f(x1,x2) = a + b*x1+b*k + c*x2 + d*x1*x2 + d*k*x2 - a - b*x1 - c*x2 - d*x1*x2
\n" ); document.write( "f(x1+k, x2) - f(x1,x2) = b*k+d*k*x2\r
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\n" ); document.write( "\n" ); document.write( "Answer: b*k+d*k*x2
\n" ); document.write( "You can factor this into (b+d*x2)*k\r
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\n" ); document.write( "\n" ); document.write( "Be sure not to mix up x2 with x^2
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