document.write( "Question 401463: How do I graph points (i.e (0,0), (3,-2), (4,-5)) on a coordinate plane? \n" ); document.write( "
Algebra.Com's Answer #285062 by lwsshak3(11628)\"\" \"About 
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How do I graph points (i.e (0,0), (3,-2), (4,-5)) on a coordinate plane?\r
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\n" ); document.write( "\n" ); document.write( "Remember the form of a quadratic equation:
\n" ); document.write( "y=ax^2+bx+c
\n" ); document.write( "We do not know whether this is a quadratic equation, but we can try to find a, b, and c, then graph it to find out if it is a quadratic equation.\r
\n" ); document.write( "\n" ); document.write( "for coordinates(0,0), 0=a(0^2)+b*0+c
\n" ); document.write( "0=c
\n" ); document.write( "c=0
\n" ); document.write( "for coordinates(3,-2), -2=a(3^2)+3b+c
\n" ); document.write( "-2=9a+3b+c
\n" ); document.write( "9a+3b+c=-2
\n" ); document.write( "for coordinates(4,-5), -5=a(4^2)+4b+c
\n" ); document.write( "-5=a(16)+4b+c
\n" ); document.write( "16a+4b+c=-5\r
\n" ); document.write( "\n" ); document.write( "we now have 3 equations with 3 unknowns, but c=0, so we only have two of the unknowns, a and b, to solve\r
\n" ); document.write( "\n" ); document.write( "9a+3b=-2
\n" ); document.write( "16a+4b=-5
\n" ); document.write( "multiply first equation by 4, and second equation by -3
\n" ); document.write( "36a+12b=-8
\n" ); document.write( "-48a-12b=+15
\n" ); document.write( "-12a=7
\n" ); document.write( "a=-7/12
\n" ); document.write( "b=(-2-9a)/3
\n" ); document.write( " =((-8/4-(9*-7/12))/3
\n" ); document.write( " =(-8/4+21/4)/3
\n" ); document.write( " =(13/4)/3
\n" ); document.write( "b=13/12
\n" ); document.write( "we now have an equation which appears to be a parabola.
\n" ); document.write( "f(x)=-(7/12)x^2+(13/12)x+0\r
\n" ); document.write( "\n" ); document.write( "see the graph below: note the 3 given coordinates,(0,0),(3,-2),and (4,-5) on the curve \r
\n" ); document.write( "\n" ); document.write( "\"+graph%28+300%2C+200%2C+-6%2C+5%2C+-5%2C+5%2C+-%287%2F12%29x%5E2%2B%2813%2F12%29x%2B0%29+\"\r
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