document.write( "Question 551022: y=(x-3)(-x-4)
\n" ); document.write( "y=x^2-16 \n" ); document.write( "
Algebra.Com's Answer #359470 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
y=(x-3)(-x-4)
\n" ); document.write( "y=x^2-16
\n" ); document.write( "Write y = y, and solve for x
\n" ); document.write( "x^2 - 16 = (x-3)(-x-4)
\n" ); document.write( "FOIL
\n" ); document.write( "x^2 - 16 = -x^2 - 4x + 3x + 12
\n" ); document.write( "x^2 - 16 = -x^2 - x + 12
\n" ); document.write( "Combine like terms on the left
\n" ); document.write( "x^2 + x^2 + x - 12 - 16 = 0
\n" ); document.write( "2x^2 + x - 28 = 0
\n" ); document.write( "Factors to
\n" ); document.write( "(2x-7)(x+4) = 0
\n" ); document.write( "two solutions
\n" ); document.write( "2x = 7
\n" ); document.write( "x = 3.5
\n" ); document.write( "and
\n" ); document.write( "x = -4
\n" ); document.write( ":
\n" ); document.write( "Check this using x=-4
\n" ); document.write( "y = x^2 - 16
\n" ); document.write( "y = (-4)^2 - 16
\n" ); document.write( "y = 16 - 16
\n" ); document.write( "y = 0
\n" ); document.write( "and\r
\n" ); document.write( "\n" ); document.write( "y = (-4-3)(-(-4)-4)
\n" ); document.write( "y = -7*(4-4)
\n" ); document.write( "y = 0
\n" ); document.write( ":
\n" ); document.write( "You can check x=3.5
\n" ); document.write( ":
\n" ); document.write( "Graph the two original equations, you can they intersect when x=-4 and x=3.5
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-6%2C+6%2C+-10%2C+10%2C+x%5E2-16%2C+%28x-3%29%28-x-4%29%29+\"
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