Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Let 
f(x)=root(3)(cos(pi*x)).
Below is Issac's attempt to write a formal justification for the fact that the equation 
f(x)=0.1 has a solution where 
1.5 <= x <= 2.
Is Issac's justification complete? If not, why?
Issac's justification:

{:[f(1.5)=0" and "],[f(2)=1", so "],[f(1.5) < 0.1 < f(2).]:}
So, according to the intermediate value theorem, 
f(x)=0.1 must have a solution when 
x is between 
x=1.5 and 
x=2.
Choose 1 answer:
(A) Yes, Issac's justification is complete.
(B) No, Issac didn't establish that 0.1 is between 
f(1.5) and 
f(2).
(C) No, Issac didn't establish that 
f is continuous.

Let f(x)=cos(πx)3 f(x)=\sqrt[3]{\cos (\pi \cdot x)} .\newlineBelow is Issac's attempt to write a formal justification for the fact that the equation f(x)=0.1 f(x)=0.1 has a solution where 1.5x2 1.5 \leq x \leq 2 .\newlineIs Issac's justification complete? If not, why?\newlineIssac's justification:\newline\[ \begin{array}{l} f(1.5)=0 \text { and } \\ f(2)=1 \text {, so } \\ f(1.5)<0.1

Full solution

Q. Let f(x)=cos(πx)3 f(x)=\sqrt[3]{\cos (\pi \cdot x)} .\newlineBelow is Issac's attempt to write a formal justification for the fact that the equation f(x)=0.1 f(x)=0.1 has a solution where 1.5x2 1.5 \leq x \leq 2 .\newlineIs Issac's justification complete? If not, why?\newlineIssac's justification:\newlinef(1.5)=0 and f(2)=1, so f(1.5)<0.1<f(2). \begin{array}{l} f(1.5)=0 \text { and } \\ f(2)=1 \text {, so } \\ f(1.5)<0.1<f(2) . \end{array} \newlineSo, according to the intermediate value theorem, f(x)=0.1 f(x)=0.1 must have a solution when x x is between x=1.5 x=1.5 and x=2 x=2 .\newlineChoose 11 answer:\newline(A) Yes, Issac's justification is complete.\newline(B) No, Issac didn't establish that 00.11 is between f(1.5) f(1.5) and f(2) f(2) .\newline(C) No, Issac didn't establish that f f is continuous.
  1. Check Continuity: To apply the Intermediate Value Theorem (IVT), we need to ensure that the function f(x)f(x) is continuous on the interval [1.5,2][1.5, 2] and that the value 0.10.1 lies between f(1.5)f(1.5) and f(2)f(2).
  2. Verify Function Values: First, we need to check if f(x)f(x) is continuous on the interval [1.5,2][1.5, 2]. The function f(x)=cos(πx)3f(x) = \sqrt[3]{\cos(\pi x)} is continuous because the cube root function and the cosine function are both continuous everywhere.
  3. Calculate f(1.5)f(1.5): Next, we need to verify Issac's claims about the values of f(1.5)f(1.5) and f(2)f(2). We calculate f(1.5)f(1.5) and f(2)f(2) to ensure that 0.10.1 is indeed between these two values.
  4. Calculate f(2)f(2): Calculate f(1.5)=cos(π1.5)3f(1.5) = \sqrt[3]{\cos(\pi\cdot1.5)}. Since cos(π1.5)=cos(3π2)=0\cos(\pi\cdot1.5) = \cos(\frac{3\pi}{2}) = 0, we have f(1.5)=03=0f(1.5) = \sqrt[3]{0} = 0.
  5. Confirm Value Range: Calculate f(2)=cos(π2)3f(2) = \sqrt[3]{\cos(\pi\cdot 2)}. Since cos(π2)=cos(2π)=1\cos(\pi\cdot 2) = \cos(2\pi) = 1, we have f(2)=13=1f(2) = \sqrt[3]{1} = 1.
  6. Apply IVT: Now we can see that 0.10.1 is indeed between f(1.5)=0f(1.5) = 0 and f(2)=1f(2) = 1. Therefore, 0 < 0.1 < 1.
  7. Apply IVT: Now we can see that 0.10.1 is indeed between f(1.5)=0f(1.5) = 0 and f(2)=1f(2) = 1. Therefore, 0 < 0.1 < 1.Since f(x)f(x) is continuous on [1.5,2][1.5, 2] and 0.10.1 is between f(1.5)f(1.5) and f(2)f(2), by the Intermediate Value Theorem, there must be some value cc in [1.5,2][1.5, 2] such that f(1.5)=0f(1.5) = 011.

More problems from One-step inequalities: word problems