To analyze the change from \( b(x) \) to \( c(x) \), we start with the given functions:
- \( b(x) = 1.5(\sqrt{4 - x}) - 1 \)
- \( c(x) = 9(\sqrt{4 - x}) - 1 \)
Identifying the Transformation
Both functions have the same basic structure: they are both vertical transformations of the function \( \sqrt{4 - x} \). The difference between \( b(x) \) and \( c(x) \) lies in the coefficients multiplied with \( \sqrt{4 - x} \).
- Coefficient of \( b(x) \): 1.5
- Coefficient of \( c(x) \): 9
Finding the Stretch Factor
To determine the vertical stretch factor from \( b(x) \) to \( c(x) \), we can calculate the ratio of the coefficients:
\[ \text{Stretch Factor} = \frac{\text{Coefficient of } c(x)}{\text{Coefficient of } b(x)} = \frac{9}{1.5} \]
Now, calculating the ratio:
\[ \frac{9}{1.5} = 6 \]
Conclusion
The transformation from \( b(x) \) to \( c(x) \) involves a vertical stretch by a factor of 6. Therefore, the correct response is:
vertical stretch by a factor of 6.