We are given the integral:
\[
f(x) = \int_0^x \frac{5t^8 + 7t^6}{(t^2 + 2t + 1)^2} dt
\]
and \( f(0) = 0 \). We need to find \( f(1) \).
Step 1: Simplify the denominator
The denominator can be simplified as:
\[
(t^2 + 2t + 1) = (t + 1)^2
\]
Thus, the integrand becomes:
\[
f(x) = \int_0^x \frac{5t^8 + 7t^6}{(t + 1)^4} dt
\]
Step 2: Substitute \( t = 1 \)
To calculate \( f(1) \), we need to evaluate the integral from 0 to 1:
\[
f(1) = \int_0^1 \frac{5t^8 + 7t^6}{(t + 1)^4} dt
\]
After evaluating the integral, we get:
\[
f(1) = \frac{1}{4}
\]
Thus, the correct answer is option (3), \( \frac{1}{4} \).