Two convex lenses of focal length 20 cm each are placed coaxially with a separation of 60 cm between them. The image of the distant object formed by the combination is at cm from the first lens.
A common example of alpha decay is
If the domain of the function \( f(x) = \sec^{-1} \left( \frac{2x}{5x + 3} \right) \) is \( [\alpha, \beta] \cup (\gamma, \delta) \), then \( |3\alpha + 10(\beta + \gamma) + 21\delta| \) is equal to: