Question

Assume the variable f refers to the Python implementation of a continuous real function (i.e., f accepts a single float as input and returns a single float as output), and a and b refer to two float values.

Write a Python expression that refers to True if and only if the function represented by f changes its sign between a and b, i.e., the sign of f(a) is different from the sign of f(b).

(We define the sign of a number x as -1 if x is negative and +1 otherwise.)

Answer 1

Program Code Screenshot :

sign change.py - D:/Coding/Python/sign change.py (3.7.4) File Edit Format Run Options Window Help def f(x): return x*x+x-2 +1f sign changes between a and b, then f(a) f(b) will return a negative value a = 0 b - 2 If sign changes, product must be negative e - f(a) f(b) <0 print (e)

Sample Output :

RESTART: D: /Coding/Python/sign change.py True

Program Code to Copy (Please refer to the screenshot of the code to understand the indentation of the code)

def f(x):
return x*x+x-2

#If sign changes between a and b, then f(a)*f(b) will return a negative value

a = 0
b = 2

#If sign changes, product must be negative
e = f(a)*f(b)<0

print(e)

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Expression is f(a)*f(b)<0