Question
A quadratic function has its vertex at the point \( (-5,-4) \). The function passes through the point \( (8,-3) \). When written in vertex form, the function is \( f(x)=a(x-h)^{2}+k \), where: \( a= \) \( h= \) \( k= \)
Ask by Ellis Gough. in the United States
Mar 13,2025
Upstudy AI Solution
Tutor-Verified Answer
Answer
\( a = \frac{1}{169} \), \( h = -5 \), \( k = -4 \)
Solution
To find the quadratic function in vertex form \( f(x) = a(x - h)^2 + k \), we start with the known vertex and a point that the function passes through.
### Step 1: Identify known values
From the problem, we know:
- The vertex \( (h, k) = (-5, -4) \)
- The point \( (x, y) = (8, -3) \)
### Step 2: Substitute known values into the vertex form
We can substitute \( h \) and \( k \) into the vertex form:
\[
f(x) = a(x + 5)^2 - 4
\]
### Step 3: Use the point to find \( a \)
Now we will use the point \( (8, -3) \) to find the value of \( a \). We substitute \( x = 8 \) and \( f(x) = -3 \) into the equation:
\[
-3 = a(8 + 5)^2 - 4
\]
### Step 4: Simplify the equation
Calculating \( (8 + 5)^2 \):
\[
(8 + 5)^2 = 13^2 = 169
\]
Now substitute this back into the equation:
\[
-3 = a(169) - 4
\]
### Step 5: Solve for \( a \)
Add 4 to both sides:
\[
-3 + 4 = 169a
\]
\[
1 = 169a
\]
Now divide by 169:
\[
a = \frac{1}{169}
\]
### Final Values
Now we can summarize the values:
- \( a = \frac{1}{169} \)
- \( h = -5 \)
- \( k = -4 \)
Thus, the values are:
- \( a = \frac{1}{169} \)
- \( h = -5 \)
- \( k = -4 \)
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Bonus Knowledge
To write the quadratic function in vertex form, we first identify the vertex coordinates: \( h = -5 \) and \( k = -4 \). This means our function starts as \( f(x) = a(x + 5)^2 - 4 \). Next, we use the point \( (8, -3) \) to find the value of \( a \). Plugging in \( x = 8 \) and \( f(x) = -3 \): \[ -3 = a(8 + 5)^2 - 4 \] \[ -3 = a(13)^2 - 4 \] \[ -3 = 169a - 4 \] \[ 1 = 169a \] \[ a = \frac{1}{169} \] So the quadratic function in vertex form is: \[ f(x) = \frac{1}{169}(x + 5)^2 - 4 \] In summary: \( a = \frac{1}{169} \) \( h = -5 \) \( k = -4 \)