Question 1016603
Use the general form of a quadratic, {{{y=ax^2+bx+c}}}
{{{9=a(0)^2+b(0)+c}}}
{{{c=9}}}
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{{{15=a(2)^2+b(2)+9}}}
{{{4a+2b=6}}}
1.{{{2a+b=3}}}
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{{{5=a(4)^2+b(4)+9}}}
{{{16a+4b=-4}}}
2.{{{4a+b=-1}}}
So then subtracting eq. 1 from eq. 2,
{{{4a+b-2a-b=-1-3}}}
{{{2a=-4}}}
{{{a=-2}}}
and finally,
{{{2(-2)+b=3}}}
{{{-4+b=3}}}
{{{b=7}}}
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{{{y=-2x^2+7x+9}}}
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