document.write( "Question 1177973: Find the value of k if (x^3-x^2-5x-2)(x^4+x^3+kx^2-5x+2)=x^7-4x^5-14x^4-5x^3+19x^2-4. \n" ); document.write( "
Algebra.Com's Answer #807157 by greenestamps(13200)\"\" \"About 
You can put this solution on YOUR website!


\n" ); document.write( "The answer can be obtained with FAR less work than shown by the other tutor....

\n" ); document.write( "

\n" ); document.write( "In the equation, k is the coefficient of the x^2 term. So look at ANY one coefficient in the product of a term which is x^2 or a higher power of x.

\n" ); document.write( "Example: The coefficient of the x^2 term in the product is 19. That coefficient comes from (1) the constant term in the first expression times the x^2 term in the second, (2) the product of the linear terms in the two expressions, and (3) the x^2 term in the first expression and the constant term in the second:

\n" ); document.write( "\"19+=+%28-1%29%282%29%2B%28-5%29%28-5%29%2B%28-2%29%28k%29\"
\n" ); document.write( "\"19+=+-2%2B25-2k\"
\n" ); document.write( "\"2k+=+4\"
\n" ); document.write( "\"k+=+2\"

\n" ); document.write( "ANSWER: k=2

\n" ); document.write( "I could have used any other coefficient of the product of a term with degree 2 or higher.

\n" ); document.write( "Second example, using the coefficient of the x^4 term in the product:

\n" ); document.write( "\"-14+=+%281%29%28-5%29%2B%28-1%29%28k%29%2B%28-5%29%281%29%2B%28-2%29%281%29\"
\n" ); document.write( "\"-14+=+-5-k-5-2\"
\n" ); document.write( "\"k+=+2\"

\n" ); document.write( "
\n" ); document.write( "
\n" );