The focal length of convex tens is `f` and the distance of an object from the principal focus is x. The ratio of the size of the real image to the size of the object is

Explanation

To solve the problem, we need to find the ratio of the size of the real image to the size of the object for a convex lens, given the focal length \( f \) and the distance of the object from the principal focus \( x \).

### Step-by-Step Solution:

1. **Understanding the Setup**:
- We have a convex lens with a focal length \( f \).
- An object is placed at a distance \( x \) from the principal focus of the lens.

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