document.write( "Question 105257This question is from textbook
\n" ); document.write( ": what can a and k be so both points are on the graph of function?
\n" ); document.write( "points are (1,11) and (2,-19); function is y= a(x+1)^2 + k
\n" ); document.write( "how can i find the function so that both poitns are on the graph??
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Algebra.Com's Answer #76600 by Earlsdon(6294)\"\" \"About 
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One way to do these is to substitute the x- and y-values from the given points into the equation, thus giving you a system of equations with two unknowns (a and k). Then solve the system of equations for the two unknowns.
\n" ); document.write( "\"y+=+a%28x%2B1%29%5E2%2Bk\" Substitute x = 1 and y = 11 from the first point (1, 11) to get the first equation.
\n" ); document.write( "\"11+=+a%281%2B1%29%5E2%2Bk\" Simplify.
\n" ); document.write( "\"11+=+4a%2Bk\"
\n" ); document.write( "Second equation:
\n" ); document.write( "\"y+=+a%28x%2B1%29%5E2%2Bk\" Substitute the x- and y-values from the second point (2, -19) to get the second equation:
\n" ); document.write( "\"-19+=+a%282%2B1%29%5E2%2Bk\" Simplify.
\n" ); document.write( "\"-19+=+9a%2Bk\"
\n" ); document.write( "So now you have the two equatios:
\n" ); document.write( "1) \"11+=+4a%2Bk\" and
\n" ); document.write( "2) \"-19+=+9a%2Bk\" You can solve these by any of the accepted methods for solving systems of equations. Let's use elimination by subtracting equation 1) from equation 2) and solving for a.
\n" ); document.write( "\"-30+=+5a\" Divide both sides by 5.
\n" ); document.write( "\"a+=+-6\" Now substitute this value of a into either equation 1) or equation 2) and solve for k. Let's use equation 1)
\n" ); document.write( "\"11+=+4a%2Bk\" Substitute a = -6
\n" ); document.write( "\"11+=+4%28-6%29%2Bk\"
\n" ); document.write( "\"11+=+-24%2Bk\" Add 24 to both sides.
\n" ); document.write( "\"k+=+35\"
\n" ); document.write( "Check: Into the original equation, substitute a = -6 and k = 35.
\n" ); document.write( "\"y+=+-6%28x%2B1%29%5E2%2B35\"
\n" ); document.write( "Now let's see if the two given points (1, 11) and (2, -19) satisfy this equation.
\n" ); document.write( "\"11+=+-6%281%2B1%29%5E2%2B35\"
\n" ); document.write( "\"11+=+-6%284%29%2B35\"
\n" ); document.write( "\"11+=+-24%2B35\"
\n" ); document.write( "\"11+=+11\" Ok for the first point.
\n" ); document.write( "\"-19+=+-6%282%2B1%29%5E2%2B35\"
\n" ); document.write( "\"-19+=+-6%289%29%2B35\"
\n" ); document.write( "\"-19+=+-54%2B35\"
\n" ); document.write( "\"-19+=+-19\" Ok for the second point.
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