Math Problem Statement

Suppose lim(x→2) f(x) = 7 and lim(x→2) g(x) = -7. Find lim(x→2) (-7f(x)^3 + 6f(x)^2 + 4f(x) + 6g(x)^3 + 10g(x) - 4x^2 - 8).

Solution

We are given the following information:

limx2f(x)=7andlimx2g(x)=7\lim_{x \to 2} f(x) = 7 \quad \text{and} \quad \lim_{x \to 2} g(x) = -7

We are tasked with finding:

limx2(7f(x)3+6f(x)2+4f(x)+6g(x)3+10g(x)4x28)\lim_{x \to 2} \left( -7f(x)^3 + 6f(x)^2 + 4f(x) + 6g(x)^3 + 10g(x) - 4x^2 - 8 \right)

Step-by-step solution:

Step 1: Substitute the limit values of f(x)f(x), g(x)g(x), and xx.

We can directly substitute limx2f(x)=7\lim_{x \to 2} f(x) = 7, limx2g(x)=7\lim_{x \to 2} g(x) = -7, and limx2x=2\lim_{x \to 2} x = 2 into the expression:

7f(x)3+6f(x)2+4f(x)+6g(x)3+10g(x)4x28-7f(x)^3 + 6f(x)^2 + 4f(x) + 6g(x)^3 + 10g(x) - 4x^2 - 8

Substituting the given values:

=7(7)3+6(7)2+4(7)+6(7)3+10(7)4(2)28= -7(7)^3 + 6(7)^2 + 4(7) + 6(-7)^3 + 10(-7) - 4(2)^2 - 8

Step 2: Simplify each term.

  • 73=3437^3 = 343, so 7(7)3=7(343)=2401-7(7)^3 = -7(343) = -2401.
  • 72=497^2 = 49, so 6(7)2=6(49)=2946(7)^2 = 6(49) = 294.
  • 4(7)=284(7) = 28.
  • (7)3=343(-7)^3 = -343, so 6(7)3=6(343)=20586(-7)^3 = 6(-343) = -2058.
  • 10(7)=7010(-7) = -70.
  • 22=42^2 = 4, so 4(2)2=4(4)=16-4(2)^2 = -4(4) = -16.
  • The constant 8-8 remains as is.

Step 3: Add up the terms.

=2401+294+28205870168= -2401 + 294 + 28 - 2058 - 70 - 16 - 8

Now, simplify:

= -2401 - 2058 + 294 + 28 - 70 - 16 - 8 = -4459 + 350 - 94 = -4459 + 256 = -4203$$ Thus, the value of the limit is $$\boxed{-4203}$$. Would you like further details on any step, or have any questions? ### Relative questions: 1. How are limits of composite functions evaluated? 2. How do you handle the limit of a polynomial function as $$x \to a$$? 3. What are the properties of limits used in this problem? 4. How does substitution work in limit problems like this? 5. How can we confirm that a function is continuous at a point? ### Tip: When dealing with limits of complex expressions, remember to use the property that the limit of a sum is the sum of the limits, assuming each limit exists.

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Math Problem Analysis

Mathematical Concepts

Limits
Substitution in Limits
Polynomials
Continuity

Formulas

lim(x→a) [f(x) + g(x)] = lim(x→a) f(x) + lim(x→a) g(x)
Substitution method for continuous functions

Theorems

Limit of a sum is the sum of the limits
Limit of a product is the product of the limits

Suitable Grade Level

Undergraduate Calculus (Calculus I or II)