document.write( "Question 919274: I am given three points on a graph (0, 1.8) (2,4) and (4,3) and am asked to find the equation of the parabola that these points pass through. I know that this parabola will be a maximum, and the y-intercept is at 1.8.
\n" ); document.write( "I have tried putting the equations into each other by plugging in each point to their own equation, and then solving from that. I must have gone wrong somewhere because I ended up with y= 0.23x^2 - 0.64x + 1.8. I don't know how to move on, could you please help? \n" ); document.write( "
Algebra.Com's Answer #557614 by lwsshak3(11628)\"\" \"About 
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I am given three points on a graph (0, 1.8) (2,4) and (4,3) and am asked to find the equation of the parabola that these points pass through.
\n" ); document.write( "***
\n" ); document.write( "Standard form of equation for a parabola:
\n" ); document.write( "y=Ax^2+Bx+c
\n" ); document.write( "For given points on parabola:
\n" ); document.write( "(0,1.8) 1.8=0A+0B+C
\n" ); document.write( "(2,4) 4=4A+2B+C
\n" ); document.write( "(4,3) 3=16A+4B+C
\n" ); document.write( "..
\n" ); document.write( "C=1.8 (fm 1st eq)
\n" ); document.write( "4=4A+2B+1.8
\n" ); document.write( "3=16A+4B+1.8
\n" ); document.write( "..
\n" ); document.write( "4A+2B=2.2
\n" ); document.write( "16A+4B=1.2
\n" ); document.write( "..
\n" ); document.write( "16A+8B=8.8 (mult. eq by4)
\n" ); document.write( "16A+4B=1.2
\n" ); document.write( "subtract:
\n" ); document.write( "4B=7.6
\n" ); document.write( "B=1.9
\n" ); document.write( "4A=2.2-2B2.2-3.8=-1.6
\n" ); document.write( "A=-0.4
\n" ); document.write( "..
\n" ); document.write( "A=-0.4
\n" ); document.write( "B=1.9
\n" ); document.write( "C=1.8
\n" ); document.write( "Equation of parabola: y=-0.4x^2+1.9x+1.8
\n" ); document.write( "..
\n" ); document.write( "Check:
\n" ); document.write( "4A+2B+C=4*(-0.4)+2*1.9+1.8=4
\n" ); document.write( "16A+4B+C=16*(-0.4)+4*1.9+1.8=3 \n" ); document.write( "
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