We need to prove, using the epsilon-delta definition of a limit, that $\lim_{x \to -\frac{3}{2}} \frac{9 - 4x^2}{3 + 2x} = 6$.

AnalysisLimitsEpsilon-Delta DefinitionCalculus
2025/6/26

1. Problem Description

We need to prove, using the epsilon-delta definition of a limit, that limx3294x23+2x=6\lim_{x \to -\frac{3}{2}} \frac{9 - 4x^2}{3 + 2x} = 6.

2. Solution Steps

We want to show that for any ϵ>0\epsilon > 0, there exists a δ>0\delta > 0 such that if 0<x(32)<δ0 < |x - (-\frac{3}{2})| < \delta, then 94x23+2x6<ϵ|\frac{9 - 4x^2}{3 + 2x} - 6| < \epsilon.
First, let's simplify the expression inside the absolute value:
94x23+2x6=94x26(3+2x)3+2x=94x21812x3+2x=4x212x93+2x|\frac{9 - 4x^2}{3 + 2x} - 6| = |\frac{9 - 4x^2 - 6(3 + 2x)}{3 + 2x}| = |\frac{9 - 4x^2 - 18 - 12x}{3 + 2x}| = |\frac{-4x^2 - 12x - 9}{3 + 2x}|.
We can factor the numerator:
4x212x9=(4x2+12x+9)=(2x+3)2-4x^2 - 12x - 9 = -(4x^2 + 12x + 9) = -(2x + 3)^2.
So, we have:
(2x+3)23+2x=(2x+3)(2x+3)2x+3|\frac{-(2x + 3)^2}{3 + 2x}| = |\frac{-(2x + 3)(2x + 3)}{2x + 3}|.
As x32x \to -\frac{3}{2}, 2x+302x + 3 \neq 0, so we can simplify further to:
(2x+3)=2x+3=2(x+32)=2x+32=2x(32)|-(2x + 3)| = |2x + 3| = |2(x + \frac{3}{2})| = 2|x + \frac{3}{2}| = 2|x - (-\frac{3}{2})|.
Now we want to find a δ>0\delta > 0 such that if 0<x(32)<δ0 < |x - (-\frac{3}{2})| < \delta, then 2x(32)<ϵ2|x - (-\frac{3}{2})| < \epsilon.
So, 2x+32<ϵ2|x + \frac{3}{2}| < \epsilon.
Dividing by 2, we get x+32<ϵ2|x + \frac{3}{2}| < \frac{\epsilon}{2}.
Thus, we can choose δ=ϵ2\delta = \frac{\epsilon}{2}.
Let ϵ>0\epsilon > 0. Choose δ=ϵ2\delta = \frac{\epsilon}{2}.
If 0<x(32)<δ0 < |x - (-\frac{3}{2})| < \delta, then
94x23+2x6=2x+32=2x(32)<2δ=2(ϵ2)=ϵ|\frac{9 - 4x^2}{3 + 2x} - 6| = 2|x + \frac{3}{2}| = 2|x - (-\frac{3}{2})| < 2\delta = 2(\frac{\epsilon}{2}) = \epsilon.

3. Final Answer

For any ϵ>0\epsilon > 0, choose δ=ϵ2\delta = \frac{\epsilon}{2}. Then, if 0<x(32)<δ0 < |x - (-\frac{3}{2})| < \delta, we have 94x23+2x6<ϵ|\frac{9 - 4x^2}{3 + 2x} - 6| < \epsilon. Therefore, limx3294x23+2x=6\lim_{x \to -\frac{3}{2}} \frac{9 - 4x^2}{3 + 2x} = 6.

Related problems in "Analysis"

The problem asks us to draw the tangent line to the curve $y = 3x^5 - 5x^4$ at the inflection point ...

CalculusDerivativesTangent LinesInflection PointsCurve Analysis
2025/6/29

The problem asks us to determine the concavity of the given curves and find their inflection points,...

CalculusDerivativesSecond DerivativeConcavityInflection Points
2025/6/29

The problem asks to find the following limits of the function $f(x)$ based on the given graph: $\lim...

LimitsFunctionsGraphical AnalysisAsymptotes
2025/6/28

The problem asks us to analyze the graph of the function $f(x)$, which is composed of a parabola, a ...

LimitsFunctionsPiecewise FunctionsAsymptotes
2025/6/28

The problem asks us to evaluate four limits based on the provided graph of a function $f(x)$. The li...

LimitsFunctionsGraph AnalysisOne-sided Limits
2025/6/28

The problem asks us to evaluate three limits, $A$, $B$, and $C$. $A = \lim_{x\to1} \frac{1+x}{\sqrt{...

LimitsCalculusIndeterminate FormsRationalizationL'Hopital's Rule (implied)
2025/6/28

The problem asks us to find the surface area of the solid generated by revolving the curve $y = x^{3...

CalculusSurface AreaSolid of RevolutionIntegrationDefinite IntegralApproximation
2025/6/28

The problem asks to find the volume of the solid generated by revolving the region bounded by the cu...

CalculusVolume of RevolutionIntegrationWasher Method
2025/6/28

The problem provides a function $f(x) = -x + 4 + \ln(\frac{x+1}{x-1})$ defined on the interval $(1, ...

LimitsDerivativesAsymptotesFunction AnalysisTangent LinesLogarithmic Functions
2025/6/28

Find the derivative of the function $g(x) = x^2 - 8\ln{x} - 1$.

CalculusDifferentiationDerivativesLogarithmic Functions
2025/6/28