document.write( "Question 204619: I need to find a quadratic equation for the following table
\n" ); document.write( "x y
\n" ); document.write( "0 0
\n" ); document.write( "2.2 30
\n" ); document.write( "2.9 40
\n" ); document.write( "4.0 50
\n" ); document.write( "5.0 60
\n" ); document.write( "6.5 70
\n" ); document.write( "8.0 80
\n" ); document.write( "9.0 90
\n" ); document.write( "11.8 100
\n" ); document.write( "This is an excel problem. but i dont know how to make excel do a quadratic equation. \n" ); document.write( "
Algebra.Com's Answer #154465 by ankor@dixie-net.com(22740)\"\" \"About 
You can put this solution on YOUR website!
I need to find a quadratic equation for the following table
\n" ); document.write( "x y
\n" ); document.write( "0 0
\n" ); document.write( "2.2 30
\n" ); document.write( "2.9 40
\n" ); document.write( "4.0 50
\n" ); document.write( "5.0 60
\n" ); document.write( "6.5 70
\n" ); document.write( "8.0 80
\n" ); document.write( "9.0 90
\n" ); document.write( "11.8 100
\n" ); document.write( ":
\n" ); document.write( "using the form y = ax^2 + bx + c
\n" ); document.write( "x=0, y=0, tells us that c = 0
\n" ); document.write( ":
\n" ); document.write( "Use two coordinates to find a & b
\n" ); document.write( "x = 4, y = 50
\n" ); document.write( "x = 9, y = 90
\n" ); document.write( ":
\n" ); document.write( "x = 4
\n" ); document.write( "16a + 4b = 50
\n" ); document.write( ":
\n" ); document.write( "x = 9
\n" ); document.write( "81a + 9b = 90
\n" ); document.write( ":
\n" ); document.write( "use elimination, mult the 1st equation by 9, the 2nd equation by 4:
\n" ); document.write( "144a + 36b = 450
\n" ); document.write( "324a + 36b = 360
\n" ); document.write( "------------------ subtraction eliminates b
\n" ); document.write( "-180a = 90
\n" ); document.write( "a = \"90%2F%28-180%29\"
\n" ); document.write( "a = -.5
\n" ); document.write( "find b using the 1st equation
\n" ); document.write( "16(-.5) + 4b = 50
\n" ); document.write( "-8 + 4b = 50
\n" ); document.write( "4b = 50 + 8
\n" ); document.write( "4b = 58
\n" ); document.write( "b = \"58%2F4\"
\n" ); document.write( "b = 14.5
\n" ); document.write( ":
\n" ); document.write( "The equation:
\n" ); document.write( "y = -.5x^2 + 14.5x
\n" ); document.write( ":
\n" ); document.write( "The graph
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-10%2C+36%2C+-20%2C+110%2C+-.5x%5E2%2B14.5x%29+\"
\n" ); document.write( ":
\n" ); document.write( "This satifys the data approximately; actual values in brackets:
\n" ); document.write( "x y
\n" ); document.write( "0 0
\n" ); document.write( "2.2 30 (29.5)
\n" ); document.write( "2.9 40 (37.8)
\n" ); document.write( "4.0 50 (50)
\n" ); document.write( "5.0 60 (60)
\n" ); document.write( "6.5 70 (73)
\n" ); document.write( "8.0 80 (84)
\n" ); document.write( "9.0 90 (90)
\n" ); document.write( "11.8 100 (101.5\r
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