document.write( "Question 168001: a wire 10 cm long is cut into two pieces, one of length x and the other of 10 - x. each piece is bent into the shape of a square
\n" ); document.write( "(a) find a function that models the total area enclosed by the two squares.
\n" ); document.write( "(b) Find the Value of x that minimizes the total area of the two squares
\n" ); document.write( "

Algebra.Com's Answer #123862 by gonzo(654)\"\" \"About 
You can put this solution on YOUR website!
area of a square is s^2 where s is the length of each side.
\n" ); document.write( "-----
\n" ); document.write( "the wire is cut into 2 lengths and forms a square with each.
\n" ); document.write( "-----
\n" ); document.write( "the wire of x length forms 4 sides with the length of each side equal to x/4.
\n" ); document.write( "-----
\n" ); document.write( "the wire of (10-x) length forms 4 sides with the length of each side equal to (10-x)/4.
\n" ); document.write( "-----
\n" ); document.write( "area of the square made by the wire of x length is \"%28x%2F4%29%5E2\"
\n" ); document.write( "this equals \"x%5E2+%2F+4%5E2\" which equals \"x%5E2%2F16\"
\n" ); document.write( "-----
\n" ); document.write( "area of the square made by the wire of (10-x) length is \"%28%2810-x%29%2F4%29%5E2\".
\n" ); document.write( "this equals \"%2810-x%29%5E2+%2F+4%5E2\" which equals \"%2810-x%29%5E2+%2F+16\".
\n" ); document.write( "-----
\n" ); document.write( "the total area enclosed by these squares is given by the equation:
\n" ); document.write( "\"f%28x%29+=+x%5E2%2F16+%2B+%2810-x%29%5E2%2F16\"
\n" ); document.write( "since the denominator is equal, this equation becomes:
\n" ); document.write( "\"f%28x%29+=+%28x%5E2+%2B+%2810-x%29%5E2%29%2F16\"
\n" ); document.write( "-----
\n" ); document.write( "since x^2 is positive, this is a quadratic equation that opens upward and points downward.
\n" ); document.write( "the point where the graph turns is a minimum point.
\n" ); document.write( "that point can be found as follows:
\n" ); document.write( "take the given formula and multiply it out to get a quadratic equation in standard form.
\n" ); document.write( "that standard form is:
\n" ); document.write( "\"%282%2Ax%5E2+-+20%2Ax+%2B+100%29%2F16\"
\n" ); document.write( "that becomes:
\n" ); document.write( "\"%28x%5E2%2F8%29+-+%2810%2Ax%2F8%29+%2B+%2850%2F8%29\"
\n" ); document.write( "-----
\n" ); document.write( "in that equation, the a coefficient is 1/8, and the b coefficient is -10/8.
\n" ); document.write( "-----
\n" ); document.write( "the formula \"-b%2F2a\" gives the minimum/ maximum point of a quadratic equation.
\n" ); document.write( "substituting, that formula becomes:
\n" ); document.write( "\"-+%28-10%2F8%29+%2F+%282%2F8%29+=+5\"
\n" ); document.write( "when x = 5, y = 3.125
\n" ); document.write( "that's the minimum value of the equation.
\n" ); document.write( "-----
\n" ); document.write( "graph of the resulting equation looks like this showing that when x = 5, y = 3.125 and the value of the equation of the squares is at a minimum.
\n" ); document.write( "\"graph%28800%2C800%2C-1%2C9%2C-10%2C10%2C%28x%5E2+%2B+%2810-x%29%5E2%29%2F16%29\"
\n" ); document.write( "
\n" ); document.write( "
\n" );