document.write( "Question 102977: The graph of the polynomial function f(x)- Ax^3+Bx^2+Cx+D,
\n" ); document.write( "where and A,B,C,and D are integers, has 3 x-intercepts at 1,2,and -6.
\n" ); document.write( "If the graph passes thought the point M(3,18),
\n" ); document.write( "determine the values of A,B,C and D.
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Algebra.Com's Answer #74899 by Fombitz(32388)\"\" \"About 
You can put this solution on YOUR website!
An x intercept is a where f(x)=0.
\n" ); document.write( "1.\"f%281%29=0\"
\n" ); document.write( "2.\"f%282%29=0\"
\n" ); document.write( "3.\"f%28-6%29=0\"
\n" ); document.write( "and you know that
\n" ); document.write( "4.\"f%283%29=18\"
\n" ); document.write( "Using the equations you get
\n" ); document.write( "1.\"f%281%29=0\"
\n" ); document.write( "\"A%2A1%5E3%2BB%2A1%5E2%2BC%2A1%2BD=0\"
\n" ); document.write( "\"A%2BB%2BC%2BD=0\"
\n" ); document.write( "2.\"f%283%29=0\"
\n" ); document.write( "\"A%2A2%5E3%2BB%2A2%5E2%2BC%2A2%2BD=0\"
\n" ); document.write( "\"8A%2B4B%2B2C%2BD=0\"
\n" ); document.write( "3.\"f%28-6%29=0\"
\n" ); document.write( "\"A%2A%28-6%29%5E3%2BB%2A%28-6%29%5E2%2BC%2A%28-6%29%2BD=0\"
\n" ); document.write( "\"-216%2AA%2B36%2AB-6%2AC%2BD=0\"
\n" ); document.write( "4.\"f%283%29=18\"
\n" ); document.write( "\"A%2A%283%29%5E3%2BB%2A%283%29%5E2%2BC%2A%283%29%2BD=18\"
\n" ); document.write( "\"27%2AA%2B9%2AB%2B3%2AC%2BD=18\"
\n" ); document.write( "Four equations, four unknowns.
\n" ); document.write( "Since you didn't specify a method to choose, I'll choose a matrix method, if that's OK.
\n" ); document.write( "These equations can be represented as three matrices G, U, and V.
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\n" ); document.write( "\"U=%28%0D%0A+matrix%28+4%2C1%2C+%0D%0A++A%2CB%2CC%2CD%0D%0A+%29%0D%0A%29\"
\n" ); document.write( "\"V=%28%0D%0A+matrix%28+4%2C1%2C+%0D%0A++0%2C0%2C0%2C18%0D%0A+%29%0D%0A%29\"
\n" ); document.write( "where [G]x[U]=[V]
\n" ); document.write( "Then [U]=[G]inv x [V]
\n" ); document.write( "Find the inverse of [G](using EXCEL) and multiply by [V]
\n" ); document.write( "The inverse of G is
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\n" ); document.write( "Since [V] has all values of zero except the last value. The solution matrix,[U], is 18 multplied by the last column of the inverse matrix or
\n" ); document.write( "\"A=1\"
\n" ); document.write( "\"B=3\"
\n" ); document.write( "\"C=-16\"
\n" ); document.write( "\"D=12\"
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