Consider the functions $f(x) = ext{sin} x$ and $g(x) = x ext{sin} x$ - HSC - SSCE Mathematics Extension 2 - Question 10 - 2018 - Paper 1
Question 10
Consider the functions $f(x) = ext{sin} x$ and $g(x) = x ext{sin} x$.
The x-coordinate of each stationary point of $f(x)$ is very close to the x-coordinate of a s... show full transcript
Worked Solution & Example Answer:Consider the functions $f(x) = ext{sin} x$ and $g(x) = x ext{sin} x$ - HSC - SSCE Mathematics Extension 2 - Question 10 - 2018 - Paper 1
Step 1
Which statement is always true?
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Answer
Since f(x)=extsinx and g(x)=xextsinx, we must analyze the stationary points of both functions.
Finding stationary points:
The stationary points of f(x)=extsinx occur where the derivative f′(x)=extcosx=0, which gives us the points x = rac{rac{ ext{(2n+1)
oindent ext{)}}}{2} ext{ where } n ext{ is an integer.}
**Behavior of stationary points for g(x)=xextsinx:
For g(x), we find stationary points via differentiated, giving g′(x)=extsinx+xextcosx=0. The solutions to this equation will provide points b.
**Comparing points a and b:
Given that the stationary points of f(x) are close to those of g(x), the value of ∣a∣<∣b∣ is the only statement that holds true, since g(x) adds the multiplicative factor of x. Hence, option C is always true.