Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

g(x)=(cos(x)-sin(x))/(cos(2x))
We want to find 
lim_(x rarr(pi)/(4))g(x).
What happens when we use direct substitution?
Choose 1 answer:
(A) The limit exists, and we found it!
(B) The limit doesn't exist (probably an asymptote).
(C) The result is indeterminate.

g(x)=cos(x)sin(x)cos(2x) g(x)=\frac{\cos (x)-\sin (x)}{\cos (2 x)} \newlineWe want to find limxπ4g(x) \lim _{x \rightarrow \frac{\pi}{4}} g(x) .\newlineWhat happens when we use direct substitution?\newlineChoose 11 answer:\newline(A) The limit exists, and we found it!\newline(B) The limit doesn't exist (probably an asymptote).\newline(C) The result is indeterminate.

Full solution

Q. g(x)=cos(x)sin(x)cos(2x) g(x)=\frac{\cos (x)-\sin (x)}{\cos (2 x)} \newlineWe want to find limxπ4g(x) \lim _{x \rightarrow \frac{\pi}{4}} g(x) .\newlineWhat happens when we use direct substitution?\newlineChoose 11 answer:\newline(A) The limit exists, and we found it!\newline(B) The limit doesn't exist (probably an asymptote).\newline(C) The result is indeterminate.
  1. Direct Substitution Attempt: Let's first attempt to use direct substitution to find the limit as xx approaches π4\frac{\pi}{4} for the function g(x)g(x). We substitute xx with π4\frac{\pi}{4} in the function g(x)g(x): g(π4)=cos(π4)sin(π4)cos(2(π4))g(\frac{\pi}{4}) = \frac{\cos(\frac{\pi}{4}) - \sin(\frac{\pi}{4})}{\cos(2 \cdot (\frac{\pi}{4}))}
  2. Substitute xx with π4\frac{\pi}{4}: Now we calculate the values of cos(π4)\cos\left(\frac{\pi}{4}\right), sin(π4)\sin\left(\frac{\pi}{4}\right), and cos(2×(π4))\cos\left(2 \times \left(\frac{\pi}{4}\right)\right) which are cos(π4)=22\cos\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}, sin(π4)=22\sin\left(\frac{\pi}{4}\right) = \frac{\sqrt{2}}{2}, and cos(2×(π4))=cos(π2)\cos\left(2 \times \left(\frac{\pi}{4}\right)\right) = \cos\left(\frac{\pi}{2}\right).
  3. Calculate Trigonometric Values: We know that cos(π2)\cos(\frac{\pi}{2}) is equal to 00. Therefore, we have:\newlineg(π4)=(2222)/0g(\frac{\pi}{4}) = (\frac{\sqrt{2}}{2} - \frac{\sqrt{2}}{2}) / 0\newlineThis simplifies to:\newlineg(π4)=00g(\frac{\pi}{4}) = \frac{0}{0}
  4. Indeterminate Form: The expression 00\frac{0}{0} is an indeterminate form. This means that direct substitution does not give us the limit, and we need to use other methods to evaluate the limit.

More problems from Power rule