Question
Evaluate the expression for each value of \( x \). \[ x^{3}-4 x^{2}-x+8 \] (a) \( x=4 \) \( \square \) \[ 60 \] (b) \( x=-4 \) \( \square \) \[ 52 \] SUBMIT ANSWER
Ask by Sanders Vega. in the United States
Jan 24,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
For \( x = 4 \), the expression equals 4. For \( x = -4 \), the expression equals -116.
Solution
It appears there may be some errors in your evaluations of the expression \( x^{3} - 4x^{2} - x + 8 \). Let's re-evaluate the expression for each given value of \( x \).
---
### (a) \( x = 4 \)
**Calculation:**
\[
\begin{align*}
x^{3} - 4x^{2} - x + 8 &= 4^{3} - 4(4)^{2} - 4 + 8 \\
&= 64 - 4(16) - 4 + 8 \\
&= 64 - 64 - 4 + 8 \\
&= (64 - 64) + (-4 + 8) \\
&= 0 + 4 \\
&= 4
\end{align*}
\]
**Result:** \( 4 \)
**Your Answer:** \( 60 \)
**Correction:** The correct value is **4**, not **60**.
---
### (b) \( x = -4 \)
**Calculation:**
\[
\begin{align*}
x^{3} - 4x^{2} - x + 8 &= (-4)^{3} - 4(-4)^{2} - (-4) + 8 \\
&= -64 - 4(16) + 4 + 8 \\
&= -64 - 64 + 4 + 8 \\
&= (-64 - 64) + (4 + 8) \\
&= -128 + 12 \\
&= -116
\end{align*}
\]
**Result:** \( -116 \)
**Your Answer:** \( 52 \)
**Correction:** The correct value is **-116**, not **52**.
---
### Summary
- **For \( x = 4 \):** The expression evaluates to **4**.
- **For \( x = -4 \):** The expression evaluates to **-116**.
If you have any further questions or need additional assistance with these calculations, feel free to ask!
Reviewed and approved by the UpStudy tutoring team
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Bonus Knowledge
To evaluate the expression \( x^{3}-4 x^{2}-x+8 \): (a) For \( x=4 \): \[ 4^{3} - 4(4^{2}) - 4 + 8 = 64 - 64 - 4 + 8 = 4 \] So the evaluation for \( x=4 \) is \( \boxed{4} \). (b) For \( x=-4 \): \[ (-4)^{3} - 4(-4)^{2} - (-4) + 8 = -64 - 64 + 4 + 8 = -116 \] So the evaluation for \( x=-4 \) is \( \boxed{-116} \).