Math Problem Statement

At what points are the following functions continuous?

Solution

The image contains multiple mathematical functions, and the task is to determine at which points each function is continuous. I will analyze each function and explain where they may fail to be continuous.

  1. i) y=1x23xy = \frac{1}{x - 2} - 3x

    • This is a rational function. It is continuous everywhere except where the denominator is zero.
    • Discontinuity: x=2x = 2.
  2. ii) y=1(x+2)2+4y = \frac{1}{(x + 2)^2} + 4

    • This is also a rational function. It is continuous except where the denominator is zero.
    • Discontinuity: x=2x = -2 (since (x+2)2=0(x + 2)^2 = 0 at x=2x = -2).
  3. iii) y=x+1x24x+3y = \frac{x + 1}{x^2 - 4x + 3}

    • The denominator factors as (x3)(x1)(x - 3)(x - 1), so the function is continuous except where the denominator is zero.
    • Discontinuities: x=1x = 1 and x=3x = 3.
  4. iv) y=x+3x23x+10y = \frac{x + 3}{x^2 - 3x + 10}

    • The denominator x23x+10x^2 - 3x + 10 has no real roots because the discriminant (3)24(1)(10)=31(-3)^2 - 4(1)(10) = -31 is negative.
    • No discontinuities, continuous for all real xx.
  5. v) y=x1+sin(x)y = |x - 1| + \sin(x)

    • The absolute value function and sine function are continuous everywhere.
    • Continuous everywhere.
  6. vi) y=1x+1x22y = \frac{1}{|x| + 1} - \frac{x^2}{2}

    • The first term 1x+1\frac{1}{|x| + 1} is continuous because x+10|x| + 1 \neq 0 for all real xx. The second term x22\frac{x^2}{2} is a polynomial, so it's also continuous everywhere.
    • Continuous everywhere.
  7. vii) y=cos(x)xy = \frac{\cos(x)}{x}

    • This is a rational function. It is continuous everywhere except where the denominator is zero.
    • Discontinuity: x=0x = 0.
  8. viii) y=x+2cos(x)y = \frac{x + 2}{\cos(x)}

    • This is also a rational function. It is continuous except where the denominator cos(x)=0\cos(x) = 0, which happens at x=π2+nπx = \frac{\pi}{2} + n\pi for integers nn.
    • Discontinuities: x=π2,3π2,5π2,x = \frac{\pi}{2}, \frac{3\pi}{2}, \frac{5\pi}{2}, \dots.
  9. ix) g(x)={x2x6x35x=3g(x) = \begin{cases} x^2 - x - 6 & x \neq 3 \\ 5 & x = 3 \end{cases}

    • The function is piecewise. For x3x \neq 3, the function is x2x6=(x3)(x+2)x^2 - x - 6 = (x - 3)(x + 2), which is continuous for all xx. However, at x=3x = 3, the function takes the value 5, which is different from the value of (x3)(x+2)(x - 3)(x + 2) at x=3x = 3, which would be 00.
    • Discontinuity: x=3x = 3.

Summary of Discontinuities:

  • i) x=2x = 2
  • ii) x=2x = -2
  • iii) x=1,x=3x = 1, x = 3
  • iv) None
  • v) None
  • vi) None
  • vii) x=0x = 0
  • viii) x=π2,3π2,x = \frac{\pi}{2}, \frac{3\pi}{2}, \dots
  • ix) x=3x = 3

Would you like more details on any of these functions or their continuity? Here are five related questions to further explore:

  1. What does the Intermediate Value Theorem say about continuous functions?
  2. How do we determine the type of discontinuity (removable, jump, etc.)?
  3. How does continuity affect the differentiability of a function?
  4. Why are rational functions often discontinuous at specific points?
  5. Can we make a discontinuous function continuous by redefining a point?

Tip: The absolute value function x|x| is continuous everywhere, but its derivative has a sharp corner at x=0x = 0, making it non-differentiable at that point.

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Math Problem Analysis

Mathematical Concepts

Continuity
Rational Functions
Absolute Value
Piecewise Functions
Trigonometric Functions

Formulas

Continuity: A function f(x) is continuous at x = a if lim(x->a) f(x) = f(a)
Rational function discontinuity: occurs where the denominator equals zero
Trigonometric functions: Discontinuous where their denominators equal zero

Theorems

Continuity Theorem
Intermediate Value Theorem

Suitable Grade Level

Grades 10-12 (High School)