Back to College Algebra

12.2 Finding Limits: Properties of Limits

Algebraic limit laws for sums, products, powers, and roots, substitution in polynomials, and clearing zero denominators in quotients.

Precalculus 2e, 12.2 Finding Limits: Properties of Limits

Status
FlagsLoading your progress…

46 exercises

Evaluating the Limit of a Function Algebraically

Evaluate lim x→3 ( 2x+5 ). \underset{x \rightarrow 3}{\lim} \left(2 x + 5\right) .

2.5

12.2 Exercise 2

Evaluate the following limit: lim x→−12 ( −2x+2 ). \underset{x \rightarrow - 12}{\lim} \left(- 2 x + 2\right) .

2.5

Evaluating the Limit of a Function Algebraically

Evaluate lim x→3 ( 5 x 2 ). \underset{x \rightarrow 3}{\lim} \left(5 x^{2}\right) .

2.5

12.2 Exercise 4

Evaluate lim x→4 ( x 3 −5). \underset{x \rightarrow 4}{\lim} \left(x^{3} - 5\right) .

2.5

Evaluating the Limit of a Polynomial Algebraically

Evaluate lim x→5 ( 2 x 3 −3x+1 ). \underset{x \rightarrow 5}{\lim} \left(2 x^{3} - 3 x + 1\right) .

2.5

12.2 Exercise 6

Evaluate the following limit: lim x→−1 ( x 4 −4 x 3 +5 ). \underset{x \rightarrow - 1}{\lim} \left(x^{4} - 4 x^{3} + 5\right) .

2.5

Evaluating a Limit of a Power

Evaluate lim x→2 ( 3x+1 ) 5 . \underset{x \rightarrow 2}{\lim} \left(3 x + 1\right)^{5} .

2.5

12.2 Exercise 8

Evaluate the following limit: lim x→−4 ( 10x+36 ) 3 . \underset{x \rightarrow - 4}{\lim} \left(10 x + 36\right)^{3} .

2.5

Evaluating the Limit of a Quotient by Factoring

Evaluate lim x→2 ( x 2 −6x+8 x−2 ). \underset{x \rightarrow 2}{\lim} \left(\frac{x^{2} - 6 x + 8}{x - 2}\right) .

2.5

12.2 Exercise 10

Evaluate the following limit: lim x→7 ( x 2 −11x+28 7−x ). \underset{x \rightarrow 7}{\lim} \left(\frac{x^{2} - 11 x + 28}{7 - x}\right) .

2.5

12.2 Exercise 12

Evaluate lim x→−5 ( 1 5 + 1 x 10+2x ). \underset{x \rightarrow - 5}{\lim} \left(\frac{\frac{1}{5} + \frac{1}{x}}{10 + 2 x}\right) .

2.5

Evaluating a Limit Containing a Root Using a Conjugate

Evaluate lim x→0 ( 25−x −5 x ). \underset{x \rightarrow 0}{\lim} \left(\frac{\sqrt{25 - x} - 5}{x}\right) .

2.5

12.2 Exercise 14

Evaluate the following limit: lim h→0 ( 16−h −4 h ). \underset{h \rightarrow 0}{\lim} \left(\frac{\sqrt{16 - h} - 4}{h}\right) .

2.5

Evaluating the Limit of a Quotient of a Function by Factoring

Evaluate lim x→4 ( 4−x x −2 ). \underset{x \rightarrow 4}{\lim} \left(\frac{4 - x}{\sqrt{x} - 2}\right) .

2.5

12.2 Exercise 16

Evaluate the following limit: lim x→3 ( x−3 x − 3 ). \underset{x \rightarrow 3}{\lim} \left(\frac{x - 3}{\sqrt{x} - \sqrt{3}}\right) .

2.5

Evaluating the Limit of a Quotient with Absolute Values

Evaluate lim x→7 | x−7 | x−7 . \underset{x \rightarrow 7}{\lim} \frac{\left|x - 7\right|}{x - 7} .

2.5

12.2 Exercise 18

Evaluate lim x→ 6 + 6−x | x−6 | . \underset{x \rightarrow 6^{+}}{\lim} \frac{6 - x}{\left|x - 6\right|} .

2.5

12.2 Exercise 19

Give an example of a type of function f f whose limit, as x x approaches a, a , is f( a ). f \left(a\right) .

2.5

12.2 Exercise 21

What does it mean to say the limit of f( x ) ,f \left(x\right) , as x x approaches c ,c , is undefined?

2.5

12.2 Exercise 23

Evaluate the limits algebraically.

lim x→2 ( −5x x 2 −1 ) \underset{x \rightarrow 2}{\lim} \left(\frac{- 5 x}{x^{2} - 1}\right)

2.5

12.2 Exercise 25

Evaluate the limits algebraically.

lim x→3 ( x 2 −9 x−3 ) \underset{x \rightarrow 3}{\lim} \left(\frac{x^{2} - 9}{x - 3}\right)

2.5

12.2 Exercise 27

Evaluate the limits algebraically.

lim x→ 3 2 ( 6 x 2 −17x+12 2x−3 ) \underset{x \rightarrow \frac{3}{2}}{\lim} \left(\frac{6 x^{2} - 17 x + 12}{2 x - 3}\right)

2.5

12.2 Exercise 29

Evaluate the limits algebraically.

lim x→3 ( x 2 −9 x 2 −5x+6 ) \underset{x \rightarrow 3}{\lim} \left(\frac{x^{2} - 9}{x^{2} - 5 x + 6}\right)

2.5

12.2 Exercise 31

Evaluate the limits algebraically.

lim x→3 ( x 2 +2x−3 x−3 ) \underset{x \rightarrow 3}{\lim} \left(\frac{x^{2} + 2 x - 3}{x - 3}\right)

2.5

12.2 Exercise 33

Evaluate the limits algebraically.

lim h→0 ( ( 2−h ) 3 −8 h ) \underset{h \rightarrow 0}{\lim} \left(\frac{\left(2 - h\right)^{3} - 8}{h}\right)

2.5

12.2 Exercise 35

Evaluate the limits algebraically.

lim h→0 ( 5−h − 5 h ) \underset{h \rightarrow 0}{\lim} \left(\frac{\sqrt{5 - h} - \sqrt{5}}{h}\right)

2.5

12.2 Exercise 37

Evaluate the limits algebraically.

lim x→9 ( x 2 −81 3− x ) \underset{x \rightarrow 9}{\lim} \left(\frac{x^{2} - 81}{3 - \sqrt{x}}\right)

2.5

12.2 Exercise 39

Evaluate the limits algebraically.

lim x→0 ( x 1+2x −1 ) \underset{x \rightarrow 0}{\lim} \left(\frac{x}{\sqrt{1 + 2 x} - 1}\right)

2.5

12.2 Exercise 41

Evaluate the limits algebraically.

lim x→4 ( x 3 −64 x 2 −16 ) \underset{x \rightarrow 4}{\lim} \left(\frac{x^{3} - 64}{x^{2} - 16}\right)

2.5

12.2 Exercise 43

Evaluate the limits algebraically.

lim x→ 2 + ( | x−2 | x−2 ) \underset{x \rightarrow 2^{+}}{\lim} \left(\frac{\left|x - 2\right|}{x - 2}\right)

2.5

12.2 Exercise 45

Evaluate the limits algebraically.

lim x→ 4 − ( | x−4 | 4−x ) \underset{x \rightarrow 4^{-}}{\lim} \left(\frac{\left|x - 4\right|}{4 - x}\right)

2.5

12.2 Exercise 47

Evaluate the limits algebraically.

lim x→4 ( | x−4 | 4−x ) \underset{x \rightarrow 4}{\lim} \left(\frac{\left|x - 4\right|}{4 - x}\right)

2.5

12.2 Exercise 49

Use the given information to evaluate the limits: lim x→c f(x)=3, \underset{x \rightarrow c}{\lim} f \left(x\right) = 3 , lim x→c g( x )=5 \underset{x \rightarrow c}{\lim} g \left(x\right) = 5.

lim x→c [ 2f(x)+ g(x) ] \underset{x \rightarrow c}{\lim} \left[ 2 f \left(x\right) + \sqrt{g \left(x\right)} \right]

2.5

12.2 Exercise 51

Use the given information to evaluate the limits: lim x→c f(x)=3, \underset{x \rightarrow c}{\lim} f \left(x\right) = 3 , lim x→c g( x )=5 \underset{x \rightarrow c}{\lim} g \left(x\right) = 5.

lim x→c f(x) g(x) \underset{x \rightarrow c}{\lim} \frac{f \left(x\right)}{g \left(x\right)}

2.5

12.2 Exercise 53

Evaluate the following limits.

lim x→2 sin( πx ) \underset{x \rightarrow 2}{\lim} \sin \left(\pi x\right)

2.5

12.2 Exercise 55

Evaluate the following limits.

f(x)={ 2 x 2 +2x+1, x≤0 x−3, x>0 ;  lim x→ 0 + f(x) f \left(x\right) = \left\{\right. \begin{matrix}2 x^{2} + 2 x + 1 , & x \leq 0 \\ x - 3 , & x > 0\end{matrix} ;\textrm{ } \underset{x \rightarrow 0^{+}}{\lim} f \left(x\right)

2.5

12.2 Exercise 57

Evaluate the following limits.

f(x)={ 2 x 2 +2x+1, x≤0 x−3, x>0 ;  lim x→0 f(x) f \left(x\right) = \left\{\right. \begin{matrix}2 x^{2} + 2 x + 1 , & x \leq 0 \\ x - 3 , & x > 0\end{matrix} ;\textrm{ } \underset{x \rightarrow 0}{\lim} f \left(x\right)

2.5

12.2 Exercise 59

Evaluate the following limits.

lim x→ 2 + (2x−[x]) \underset{x \rightarrow 2^{+}}{\lim} \left(2 x - \left[x\right]\right)

2.5

12.2 Exercise 61

Evaluate the following limits.

lim x→ 3 + x 2 x 2 −9 \underset{x \rightarrow 3^{+}}{\lim} \frac{x^{2}}{x^{2} - 9}

2.5

12.2 Exercise 63

Find the average rate of change f(x+h)−f(x) h . \frac{f \left(x + h\right) - f \left(x\right)}{h} .

f(x)=2 x 2 −1 f \left(x\right) = 2 x^{2} - 1

2.5

12.2 Exercise 65

Find the average rate of change f(x+h)−f(x) h . \frac{f \left(x + h\right) - f \left(x\right)}{h} .

f(x)= x 2 +4x−100 f \left(x\right) = x^{2} + 4 x - 100

2.5

12.2 Exercise 67

Find the average rate of change f(x+h)−f(x) h . \frac{f \left(x + h\right) - f \left(x\right)}{h} .

f(x)=cos(x) f \left(x\right) = \cos \left(x\right)

2.5

12.2 Exercise 69

Find the average rate of change f(x+h)−f(x) h . \frac{f \left(x + h\right) - f \left(x\right)}{h} .

f(x)= 1 x f \left(x\right) = \frac{1}{x}

2.5

12.2 Exercise 71

Find the average rate of change f(x+h)−f(x) h . \frac{f \left(x + h\right) - f \left(x\right)}{h} .

f(x)= x f \left(x\right) = \sqrt{x}

2.5

12.2 Exercise 75

What is the left-hand limit of the function as x x approaches 0?

2.5

12.2 Exercise 77

The height of a projectile is given by s(t)=−64 t 2 +192t s \left(t\right) = - 64 t^{2} + 192 t Find the average rate of change of the height from t=1 t = 1 second to t=1.5 t = 1.5 seconds.

2.5

Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.