We are given that $(2 + 4x^2) \le f(x)$. We need to find a correct estimate for the integral $\int_0^2 f(x) \, dx$.
2025/5/10
1. Problem Description
We are given that . We need to find a correct estimate for the integral .
2. Solution Steps
Since , we can integrate both sides of the inequality from 0 to 2:
Now, let's evaluate the integral on the left side:
Since , we have
Therefore, .
Comparing this with the given options:
A.
B.
C.
D.
Since , and , it follows that , which is very close to 14.
6
7. Also, $f(x) \ge 2 + 4x^2 \ge 2$, therefore $\int_0^2 f(x) dx \ge \int_0^2 2 dx = 4$. Therefore, option C can be ruled out. Option D is too weak of a bound, as $f(x)$ must be positive on the interval $[0, 2]$. Option B is not true, as $\int_0^2 f(x) dx \ge \frac{44}{3}$. Since $\frac{44}{3} \approx 14.6667 < 14.67$, it follows that $\int_0^2 f(x) dx \ge 14.6667$. We also know that $\int_0^2 f(x) dx \ge 14.67$ can be false, but the problem asks which of the following is a correct estimate. The integral is greater than or equal to $\frac{44}{3}$, which is about 14.67, so option A is correct.
3. Final Answer
A.