If f is continuous for all x, which of the following integrals necessarily have the same value?

Answer:
B
Step-by-step explanation:
Given the three integrals, we want to determine which integrals necessarily have the same value.
We can let the first integral be itself.
For the second integral, we can perform a u-substitution. Let u = x + a. Then:
[tex]\displaystyle du = dx[/tex]
Changing our limits of integration:
[tex]u_1=(0)+a=a \text{ and } u_2 = (b+a)+a = b+2a[/tex]
Thus, the second integral becomes:
[tex]\displaystyle \int_{0}^{b+a}f(x+a)\, dx = \int_a^{b+2a} f(u)\, du[/tex]
For the third integral, we can also perform a u-substitution. Let u = x + c. Then:
[tex]\displaystyle du = dx[/tex]
And changing our limits of integration:
[tex]\displaystyle u_1=(a-c)+c=a \text{ and } u_2=(b-c)+c=b[/tex]
Thus, our third integral becomes:
[tex]\displaystyle \int_{a-c}^{b-c}f(x+c)\, dx = \int_{a}^{b} f(u)\, du[/tex]
Since the only difference between f(x) and f(u) is the variable and both the first and third integral have the same limits of integration, our answer is B.