A convex lens of focal length `f_(1)` is kept in contact with a concave lens of focal length `f_(2)`. Find the focal length of the combination.

Explanation

To find the focal length of a combination of a convex lens and a concave lens placed in contact, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Focal Lengths**:
- Let the focal length of the convex lens be \( f_1 \) (positive value).
- Let the focal length of the concave lens be \( f_2 \) (negative value).

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