Question 1018089
Use the general vertex form,
{{{y=a(x-r[1])(x-r[2])}}}
{{{y=a(x-(-2))(x-4)}}}
{{{y=a(x+2)(x-4)}}}
Now use the point to solve for {{{a}}}.
{{{9=a(1+2)(1-4)}}}
{{{9=a(3)(-3)}}}
{{{9=-9a}}}
{{{a=-1}}}
So,
{{{y=-(x+2)(x-4)}}}
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*[illustration dc25.JPG].
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Do the second problem exactly the same way.