The input in f(5) = 23 is 5.
The function is given as:
f(x) = 4x + 3
In the above function, the input is x and the output is f(x)
This means that the input in f(5) = 23 is 5.
This is so because x = 5
Hence, the input in f(5) = 23 is 5.
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