determine in general form the rule of a quadratic function whose zeros are -8 and 2 and whose minimum is -50
Question
Answer:
Solution:
$$ f(x)=y $$
The zeros of a function are also called the roots or the factors.
$$ x=-8 $$
$$ x=2 $$
Therefore;
$$ y=(x+8)(x-2)+C $$
where C is the constant to meet the minimum value.
$$ y=x^2+6x-16+C $$
Make the equation in the form:
$$ y=a(x-h)^2+k $$
Where k is the minimum value of the function.
Therefore; Make it a perfect square trinomial by completing the square...
$$ y+16+(\frac{6}{2})^2=x^2+6x+(\frac{6}{2})^2+C $$
$$ y+16+9=x^2+6x+9+C $$
$$ y+25=(x+3)^2+C $$
$$ y=(x+3)^2+(C-25) $$
$$ k=(C-25) $$
$$ -50=C-25 $$
$$ -50+25=C $$
$$ C=-25 $$
Going back to our original equation...
$$ y=x^2+6x-16+C $$
$$ f(x)=x^2+6x-16-25 $$
$$ f(x)=x^2+6x-41 $$
ANSWER:
$$ f(x)=x^2+6x-41 $$
solved
general
11 months ago
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