The function g is defined as g(x)=ln(x2),x∈R,x<0. (i) State the domain and range of g. (ii) Give a reason why g−1 exists. (iii) Find the rule, domain and range of g−1.
Q. The function g is defined as g(x)=ln(x2),x∈R,x<0. (i) State the domain and range of g. (ii) Give a reason why g−1 exists. (iii) Find the rule, domain and range of g−1.
Define function g: The function g is defined as g(x)=ln(x2) for x<0. To find the domain of g, we need to consider the values of x for which ln(x2) is defined.Since the natural logarithm function, ln(x), is defined for x>0, and x2 is always positive for g0, the domain of g is all negative real numbers.
Find domain of g: The range of g is the set of all possible output values. Since the natural logarithm function can take any real number as its output, and x2 maps any negative x to a positive number, the range of g is all real numbers.
Find range of g: To give a reason why the inverse of g exists, we need to check if g is a one-to-one function. A function is one-to-one if each output is the result of exactly one input. Since the derivative of g(x)=ln(x2) is g′(x)=x2, which is always negative for x<0, g is strictly decreasing on its domain. Therefore, g is one-to-one and an inverse function g−1 exists.
Check one-to-one function: To find the rule of the inverse function g−1, we set y=ln(x2) and solve for x in terms of y. We exponentiate both sides to remove the natural logarithm, getting ey=x2. Since we know x is negative (from the domain of g), we take the negative square root to find x. Thus, x=−ey, and the rule for g−1 is y=ln(x2)0.
Find rule of inverse function: The domain of the inverse function g−1 is the range of the original function g, which is all real numbers, as we have established earlier.
Domain of inverse function: The range of the inverse function g−1 is the domain of the original function g, which is all negative real numbers.
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