Math Problem Statement

Given that lim(x->2) f(x) = 4, lim(x->2) g(x) = -2, lim(x->2) h(x) = 0, find the limits for the following expressions: (a) lim(x->2) [f(x) + 5g(x)] (b) lim(x->2) [g(x)]^3 (c) lim(x->2) sqrt(f(x)) (d) lim(x->2) 3f(x) / g(x) (e) lim(x->2) g(x) / h(x) (f) lim(x->2) g(x)h(x) / f(x)

Solution

Let's go through each of the given limit problems one by one using the provided information.

Given: limx2f(x)=4,limx2g(x)=2,limx2h(x)=0\lim_{x \to 2} f(x) = 4, \quad \lim_{x \to 2} g(x) = -2, \quad \lim_{x \to 2} h(x) = 0 We'll compute the limits as follows:


(a) limx2[f(x)+5g(x)]\lim_{x \to 2} [f(x) + 5g(x)]

We can split this limit using the sum rule of limits:

limx2[f(x)+5g(x)]=limx2f(x)+5limx2g(x)\lim_{x \to 2} [f(x) + 5g(x)] = \lim_{x \to 2} f(x) + 5 \cdot \lim_{x \to 2} g(x)

Substitute the given values:

=4+5(2)=410=6= 4 + 5(-2) = 4 - 10 = -6

So, the limit is 6-6.


(b) limx2[g(x)]3\lim_{x \to 2} [g(x)]^3

By the power rule of limits:

limx2[g(x)]3=(limx2g(x))3\lim_{x \to 2} [g(x)]^3 = \left(\lim_{x \to 2} g(x)\right)^3

Substitute the given value for g(x)g(x):

=(2)3=8= (-2)^3 = -8

So, the limit is 8-8.


(c) limx2f(x)\lim_{x \to 2} \sqrt{f(x)}

By the square root rule of limits:

limx2f(x)=limx2f(x)\lim_{x \to 2} \sqrt{f(x)} = \sqrt{\lim_{x \to 2} f(x)}

Substitute the given value for f(x)f(x):

=4=2= \sqrt{4} = 2

So, the limit is 2.


(d) limx23f(x)g(x)\lim_{x \to 2} \frac{3f(x)}{g(x)}

Using the quotient rule of limits:

limx23f(x)g(x)=3limx2f(x)limx2g(x)\lim_{x \to 2} \frac{3f(x)}{g(x)} = \frac{3 \cdot \lim_{x \to 2} f(x)}{\lim_{x \to 2} g(x)}

Substitute the given values for f(x)f(x) and g(x)g(x):

=342=122=6= \frac{3 \cdot 4}{-2} = \frac{12}{-2} = -6

So, the limit is 6-6.


(e) limx2g(x)h(x)\lim_{x \to 2} \frac{g(x)}{h(x)}

Using the quotient rule of limits:

limx2g(x)h(x)=limx2g(x)limx2h(x)\lim_{x \to 2} \frac{g(x)}{h(x)} = \frac{\lim_{x \to 2} g(x)}{\lim_{x \to 2} h(x)}

Substitute the given values:

=20= \frac{-2}{0}

This expression results in a division by zero, which means the limit does not exist. More specifically, the limit approaches -\infty or \infty depending on the direction of approach, but it is undefined overall.


(f) limx2g(x)h(x)f(x)\lim_{x \to 2} \frac{g(x) h(x)}{f(x)}

Using the quotient and product rules of limits:

limx2g(x)h(x)f(x)=(limx2g(x))(limx2h(x))limx2f(x)\lim_{x \to 2} \frac{g(x) h(x)}{f(x)} = \frac{\left(\lim_{x \to 2} g(x)\right) \cdot \left(\lim_{x \to 2} h(x)\right)}{\lim_{x \to 2} f(x)}

Substitute the given values for g(x)g(x), h(x)h(x), and f(x)f(x):

=(2)(0)4=04=0= \frac{(-2)(0)}{4} = \frac{0}{4} = 0

So, the limit is 0.


Summary of Results:

  • (a) 6-6
  • (b) 8-8
  • (c) 22
  • (d) 6-6
  • (e) Does not exist (division by zero)
  • (f) 00

Would you like any additional details or further explanations on any part?


Here are 5 related questions for practice:

  1. What happens if limx2g(x)=0\lim_{x \to 2} g(x) = 0 in problem (d)?
  2. How would you solve limxaf(x)g(x)\lim_{x \to a} f(x)g(x) if limxag(x)=0\lim_{x \to a} g(x) = 0?
  3. Can you explain the difference between removable and non-removable discontinuities?
  4. How does the limit definition change if g(x)g(x) \to \infty as x2x \to 2?
  5. What are the conditions for a limit to exist when dealing with quotient functions?

Tip: Always check for the possibility of dividing by zero when dealing with limit problems involving quotient functions.

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Math Problem Analysis

Mathematical Concepts

Limits
Functions
Quotient Rule
Sum Rule
Product Rule

Formulas

lim(x->c) [f(x) + g(x)] = lim(x->c) f(x) + lim(x->c) g(x)
lim(x->c) [f(x)g(x)] = lim(x->c) f(x) * lim(x->c) g(x)
lim(x->c) [f(x) / g(x)] = lim(x->c) f(x) / lim(x->c) g(x), provided lim(x->c) g(x) ≠ 0
lim(x->c) [f(x)]^n = [lim(x->c) f(x)]^n

Theorems

Limit Sum Rule
Limit Quotient Rule
Limit Power Rule
Limit Product Rule

Suitable Grade Level

Grades 10-12 (High School Calculus)