document.write( "Question 86878: please solve this problem: find the points of intersection of the straight line 7x+y=25 and the circle x^2+y^2=25 \n" ); document.write( "
Algebra.Com's Answer #62855 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
please solve this problem: find the points of intersection of the straight line 7x+y=25 and the circle x^2+y^2=25
\n" ); document.write( ":
\n" ); document.write( "7x + y = 25
\n" ); document.write( "y = (25-7x)
\n" ); document.write( ":
\n" ); document.write( "Substitute (25-7x) for y in circle equation (x^2 + y^2 = 25):
\n" ); document.write( "x^2 + (25-7x)^2 = 25
\n" ); document.write( ":
\n" ); document.write( "x^2 + 625 - 350x + 49x^2 = 25; FOILed (25-7x)(25-7x)
\n" ); document.write( ":
\n" ); document.write( "x^2 + 49x^2 - 350x + 625 - 25 = 0; combine like terms
\n" ); document.write( ":
\n" ); document.write( "50x^2 - 350x + 600 = 0; a quadratic equation
\n" ); document.write( ":
\n" ); document.write( "Simplify, divide equation by 50:
\n" ); document.write( "x^2 - 7x + 12 = 0
\n" ); document.write( ":
\n" ); document.write( "Factors to:
\n" ); document.write( "(x-3)(x-4) = 0
\n" ); document.write( "x = +3
\n" ); document.write( "and
\n" ); document.write( "x = +4
\n" ); document.write( ":
\n" ); document.write( "Substitute these x values in y = 25-7x to find points of intersection:
\n" ); document.write( "y = 25 - 7(3)
\n" ); document.write( "y = 25 - 21
\n" ); document.write( "y = +4
\n" ); document.write( ":
\n" ); document.write( "First point of intersection: 3,4
\n" ); document.write( ":
\n" ); document.write( "y = 25 - 7(4)
\n" ); document.write( "y = 25 - 28
\n" ); document.write( "y = -3
\n" ); document.write( ":
\n" ); document.write( "2nd point of intersection: 4,-3
\n" ); document.write( ":
\n" ); document.write( ":
\n" ); document.write( "Did this help? \n" ); document.write( "
\n" );