To compute a19 mod N, the modular exponential algorithms that we studied would do 8 modular multiplications (5 squarings and 3 multiplications by a). What is the minimum number of modular multiplications needed to compute a19 mod N if you are free to use any sequence of modular multiplications.)

Answer for the question:

To compute a19 mod N, the modular exponential algorithms that we studied would do 8 modular multiplications (5 squarings and 3 multiplications by a). What is the minimum number of modular multiplications needed to compute a19 mod N if you are free to use any sequence of modular multiplications.)

is given in the attachment.

Step-by-step explanation:

Option B. √x + 3

Step-by-step explanation:

f(x) = (x - 3)²

We can obtain the inverse f¯¹(x) of the above expression as follow:

f(x) = (x - 3)²

Replace f(x) with

f(x) = (x - 3)²

y = (x - 3)²

Next, interchange x and y

y = (x - 3)²

x = (y - 3)²

Make y the subject

x = (y - 3)²

Take the square root of both side

√x = y - 3

Add 3 to both side

√x + 3 = y - 3 +3

√x + 3 = y

y = √x + 3

Finally, replace y with f¯¹(x)

y = √x + 3

f¯¹(x) = √x + 3