Week 8 Practice Assignment

Week 8 Practice Assignment


Mathematics I


Multiple Select Questions (MSQ) and Matching

Question 1 (Matching)

Given:

  • Column A: Functions (i) $ f(x) = x e^x $, (ii) $ f(x) = e^{-2x} - 1 $, (iii) $ f(x) = e^x - 1 $
  • Column B: Tangent equations (a) $ y = -2x $, (b) $ y = x $, (c) $ y = 0 $
  • Column C: Figure numbers (1, 2, 3)

Solution:

  • Option 1: (i) → (b) → 3
    • Function: $ f(x) = x e^x $
    • Tangent at 0: $ f’(x) = (1 + x)e^x $, $ f’(0) = 1 $, tangent $ y = x $
    • Figure: 3
  • Option 2: (ii) → (a) → 1
    • Function: $ f(x) = e^{-2x} - 1 $
    • Tangent at 0: $ f’(x) = -2e^{-2x} $, $ f’(0) = -2 $, tangent $ y = -2x $
    • Figure: 1
  • Option 3: (iii) → (c) → 2
    • Function: $ f(x) = e^x - 1 $
    • Tangent at 0: $ f’(x) = e^x $, $ f’(0) = 1 $, but the tangent is not given as $ y = x $ here; the solution suggests $ y = 0 $ is incorrect for this function, but as per the matching, (iii) → (c) → 2 is given.
  • Option 4: (iii) → (b) → 3
    • Not correct as per function and tangent.
  • Option 5: (ii) → (a) → 1
    • Repeat of correct option above.
  • Option 6: (i) → (a) → 1
    • Incorrect.

Summary: Correct matches are:

  • (i) $ x e^x $ → (b) $ y = x $ → 3
  • (ii) $ e^{-2x} - 1 $ → (a) $ y = -2x $ → 1
  • (iii) $ e^x - 1 $ → (c) $ y = 0 $ → 2 (though this is not correct mathematically, it is the match given in the solution for the assignment)

Question 2 (Continuity and Limits)

Statement: Consider $ f(x) = e^x - 1 $ and $ g(x) = x $.

Options:

  • **(f + g)(x) = e^x - 1 + x$$
  • Is (f + g)(x) continuous at $ x = 0 $?

Solution:

  • LHL: $\lim_{x \to 0^-} (e^x - 1 + x) = 0$
  • RHL: $\lim_{x \to 0^+} (e^x - 1 + x) = 0$
  • Value at 0: $(f + g)(0) = 0$
  • Conclusion: $(f + g)(x)$ is continuous at $ x = 0 $1.

Question 3 (Limit of Product)

Statement: Find $\lim_{x \to 0} f(x)g(x)$, where $ f(x) = e^x - 1 $, $ g(x) = x $.

Solution:

  • $\lim_{x \to 0} (e^x - 1)(x) = 0$
  • Answer: $0$

Numerical Answer Type (NAT)

Question 1

Statement: Let $ f $ be a differentiable function at $ x = 1 $. The tangent line to the curve represented by the function $ f $ at the point $(1, 1)$ passes through the point $(2, 2)$. What will be the value of $ f’(1) $?

Solution:

  • Slope of tangent: $\frac{2 - 1}{2 - 1} = 1$
  • Answer: $f’(1) = 1$1

Question 2

Statement: Let $ f: \mathbb{R} \to \mathbb{R} $ be defined by $ f(x) = x^2 $ and $ g: \mathbb{R} \to \mathbb{R} $ be defined by $ g(x) = x - 5 $. Find the value of $(fg)’(1) - (f \circ g)’(1)$, where $ fg(x) = f(x)g(x) $ and $ f \circ g(x) = f(g(x)) $.

Solution:

  • Product rule: $(fg)(x) = x^2(x - 5) = x^3 - 5x^2$
    • $(fg)’(x) = 3x^2 - 10x$
    • $(fg)’(1) = 3(1)^2 - 10(1) = -7$
  • Composition rule: $(f \circ g)(x) = (x - 5)^2$
    • $(f \circ g)’(x) = 2(x - 5)$
    • $(f \circ g)’(1) = 2(1 - 5) = -8$
  • Difference: $-7 - (-8) = 1$
  • Answer: $1$1

Summary Table

Question TypeDescriptionSolution/Answer
MSQ/MatchingMatch function, tangent, figure(i) → (b) → 3, (ii) → (a) → 1, (iii) → (c) → 2
Continuity$f+g$ at $x=0$Continuous, value = 0
Limit$\lim_{x \to 0} f(x)g(x)$0
NAT$f’(1)$ for tangent1
NAT$(fg)’(1) - (f \circ g)’(1)$1

Note: The above is based on the available content from the Week 8 Practice Assignment Solution PDF1. If your PDF contains additional or different questions, please upload or specify further details. The second source2 refers to a Computational Thinking assignment, not the mathematics PDF, and is not included in this summary.

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