document.write( "Question 1141800: (a) The volume of a box is represented by the function, V(x)=x^3+5x^2+2x-8.
\n" ); document.write( "If the height of the box is represented by (x+4), determine the possible dimensions(binomials) of the box. Is there any restriction on the value of x?
\n" ); document.write( "(b) If the volume of the box is 70cm^3 determine possible whole number value(s) for x.
\n" ); document.write( "

Algebra.Com's Answer #762444 by greenestamps(13215)\"\" \"About 
You can put this solution on YOUR website!


\n" ); document.write( "(a) The volume of the box is length times width times height; you are given that the height is x+4.

\n" ); document.write( "(1) Use synthetic division to remove the factor (x+4).
\r\n" );
document.write( "\r\n" );
document.write( "  -4 |  1   5   2  -8\r\n" );
document.write( "     |     -4  -4   8\r\n" );
document.write( "     +-----------------\r\n" );
document.write( "        1   1  -2   0

\n" ); document.write( "So

\n" ); document.write( "\"x%5E3%2B5x%5E2%2B2x-8+=+%28x%2B4%29%28x%5E2%2Bx-2%29\"

\n" ); document.write( "(2) Factor the quadratic.

\n" ); document.write( "\"x%5E3%2B5x%5E2%2B2x-8+=+%28x%2B4%29%28x%2B2%29%28x-1%29\"

\n" ); document.write( "ANSWER: The possible dimensions of the box are (x-1), (x+2), and (x+4). Since dimensions of a box must be positive, the restriction is that x has to be greater than 1.

\n" ); document.write( "(b) You could use any number of methods to solve the equation

\n" ); document.write( "\"x%5E3%2B5x%5E2%2B2x-8+=+70\"

\n" ); document.write( "However, since we know x > 1 and we are looking for whole number values for x, we can quickly find the solution by logical trial and error.

\n" ); document.write( "x=2: (x-1)(x+2)(x+4) = (1)(4)(6) = 24 no...

\n" ); document.write( "x=3: (x-1)(x+2)(x+4) = (2)(5)(7) = 70 YES!

\n" ); document.write( "And clearly larger values of x will produce volumes greater than 70.

\n" ); document.write( "ANSWER: x=3 makes the volume 70
\n" ); document.write( "
\n" );