Kagome_gurl8
Find a quadratic function to model the values in the table. Predict the value of y for x = 4.
XY
13
02
335



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anonymous
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the constant must be \(2\) so you have
\[y=ax^2+bx2\] as a start
now we can set up a couple equations in \(a\) and \(b\)

anonymous
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let \(x=1\) you get
\[ab2=3\] or\[ab=1\]

anonymous
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let \(x=3\) you get \[9a+3b2=35\] or \[9a+3b=33\]

anonymous
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solve the system
\[ab=1\]\[9a+3b=33\] to get your answer

anonymous
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multiply first equation by 3, add it to the second get \[12a=36\] so \(a=3\)
therefore \(b=2\) and you get
\[y=3x^22b2\]

anonymous
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oops
\[y=3a^22x2\]

Kagome_gurl8
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so it would be y=3a^22x2;58

Kagome_gurl8
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@satellite73

anonymous
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yes for the first one

anonymous
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it would be
\[y=3x^22x2\] with an \(x\) not an \(a\)

Kagome_gurl8
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thanks so much. i've been working on this thing all weekend....

Kagome_gurl8
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wait so 4 is going to be 56?

Kagome_gurl8
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@satellite73