Question
find the x-intercept: \( y=x^{2}-4 x-5 \)
Ask by Franklin Pierce. in Saudi Arabia
Jan 23,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
The x-intercepts are at \( x = 5 \) and \( x = -1 \).
Solution
To find the **x-intercepts** of the quadratic function \( y = x^{2} - 4x - 5 \), you need to determine the points where the graph of the function crosses the x-axis. At these points, the value of \( y \) is **0**.
### Step 1: Set \( y \) to 0
\[
0 = x^{2} - 4x - 5
\]
### Step 2: Solve the Quadratic Equation
You can solve the quadratic equation \( x^{2} - 4x - 5 = 0 \) by using the **quadratic formula**:
\[
x = \frac{-b \pm \sqrt{b^{2} - 4ac}}{2a}
\]
For the given equation:
- \( a = 1 \)
- \( b = -4 \)
- \( c = -5 \)
Plugging these values into the quadratic formula:
\[
x = \frac{-(-4) \pm \sqrt{(-4)^{2} - 4(1)(-5)}}{2(1)}
\]
\[
x = \frac{4 \pm \sqrt{16 + 20}}{2}
\]
\[
x = \frac{4 \pm \sqrt{36}}{2}
\]
\[
x = \frac{4 \pm 6}{2}
\]
This gives two solutions:
1. **First solution:**
\[
x = \frac{4 + 6}{2} = \frac{10}{2} = 5
\]
2. **Second solution:**
\[
x = \frac{4 - 6}{2} = \frac{-2}{2} = -1
\]
### Step 3: State the X-Intercepts
The x-intercepts are the points where \( y = 0 \), so:
- **First x-intercept:** \( (5, 0) \)
- **Second x-intercept:** \( (-1, 0) \)
### **Conclusion**
The quadratic function \( y = x^{2} - 4x - 5 \) intersects the x-axis at the points **(5, 0)** and **(−1, 0)**.
Reviewed and approved by the UpStudy tutoring team
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Mind Expander
To find the x-intercept of the equation \( y = x^2 - 4x - 5 \), you need to set \( y \) to 0 and solve for \( x \). So, you get \( 0 = x^2 - 4x - 5 \). This can be factored into \( (x - 5)(x + 1) = 0 \). Therefore, the x-intercepts are \( x = 5 \) and \( x = -1 \). Now these points represent where the graph of the quadratic crosses the x-axis. Graphing it will show a lovely U-shaped curve, and those x-intercepts are the points where the fun curve takes a pause before continuing upwards!