Learn Without Walls

Practice Problems

20 comprehensive problems covering all Module 3 topics

How to Use These Practice Problems

These 20 problems cover all major topics from Module 3. Try to solve each problem on your own before revealing the solution. Work through them systematically to build mastery.

Topics covered: Polynomial functions (end behavior, zeros, graphing), factoring polynomials, rational functions (asymptotes, holes), and inequalities.

Section 1: Polynomial Functions (Problems 1-5)

Problem 1
End Behavior

Determine the end behavior of f(x) = -2x5 + 3x3 - x + 7

Solution

Step 1: Identify degree and leading coefficient

Degree: 5 (odd)

Leading coefficient: -2 (negative)

Step 2: Apply Leading Term Test

Odd degree + Negative leading coefficient:

As x → -∞, f(x) → +∞

As x → +∞, f(x) → -∞

Interpretation: The graph rises on the left and falls on the right.

Problem 2
Zeros & Multiplicity

For f(x) = x(x + 3)2(x - 2)3, identify all zeros, their multiplicities, and graph behavior at each zero.

Solution

Zero Multiplicity Graph Behavior
x = 0 1 (odd) Crosses x-axis
x = -3 2 (even) Touches x-axis (bounces)
x = 2 3 (odd) Crosses x-axis (flattens near crossing)

Additional information:

Total degree: 1 + 2 + 3 = 6 (even)

Leading coefficient: 1 (positive)

End behavior: Both ends point upward

Problem 3
Finding Zeros

Find all real zeros of f(x) = x3 - 2x2 - 5x + 6

Solution

Step 1: Use Rational Root Theorem

Possible rational roots: ±1, ±2, ±3, ±6

Step 2: Test x = 1

f(1) = 1 - 2 - 5 + 6 = 0 Zero found!

Step 3: Use synthetic division with x = 1

    1 |  1   -2   -5    6
      |       1   -1   -6
      |___________________
         1   -1   -6    0

Quotient: x2 - x - 6

Step 4: Factor the quotient

x2 - x - 6 = (x - 3)(x + 2)

Step 5: Complete factorization

f(x) = (x - 1)(x - 3)(x + 2)

All zeros: x = -2, 1, 3

Problem 4
Graphing

Sketch the graph of f(x) = -x3 + 4x. Include zeros, y-intercept, and end behavior.

Solution

Step 1: Factor to find zeros

f(x) = -x3 + 4x = -x(x2 - 4) = -x(x - 2)(x + 2)

Zeros: x = -2, 0, 2 (all multiplicity 1, so graph crosses at each)

Step 2: Find y-intercept

f(0) = 0, so y-intercept is (0, 0)

Step 3: Determine end behavior

Degree: 3 (odd), Leading coefficient: -1 (negative)

As x → -∞, f(x) → +∞

As x → +∞, f(x) → -∞

Step 4: Test points

f(-3) = -(-27) + 12 = 39 (positive)

f(1) = -1 + 4 = 3 (positive)

f(3) = -27 + 12 = -15 (negative)

Graph characteristics:

  • Comes from upper left (positive infinity)
  • Crosses at x = -2
  • Goes up to a local maximum between -2 and 0
  • Crosses at x = 0
  • Goes down to a local minimum between 0 and 2
  • Crosses at x = 2
  • Continues down to negative infinity
Problem 5
Polynomial Analysis

A polynomial f(x) has degree 4 with leading coefficient 3. It has zeros at x = -1 (multiplicity 2) and x = 2 (multiplicity 2). Write the polynomial in factored form and determine its end behavior.

Solution

Step 1: Write in factored form

f(x) = 3(x + 1)2(x - 2)2

Step 2: Verify degree

Degree = 2 + 2 = 4

Step 3: Determine end behavior

Degree: 4 (even)

Leading coefficient: 3 (positive)

As x → -∞, f(x) → +∞

As x → +∞, f(x) → +∞

Both ends point upward.

Additional notes:

Graph touches (bounces) at both x = -1 and x = 2 (even multiplicities)

The graph never crosses the x-axis; it touches at two points and is positive everywhere else

Section 2: Factoring Polynomials (Problems 6-10)

Problem 6
Sum of Cubes

Factor completely: 8x3 + 27

Solution

Step 1: Recognize as sum of cubes

8x3 + 27 = (2x)3 + 33

Step 2: Apply sum of cubes formula

a3 + b3 = (a + b)(a2 - ab + b2)

where a = 2x and b = 3

Step 3: Substitute

(2x + 3)[(2x)2 - (2x)(3) + 32]

(2x + 3)(4x2 - 6x + 9)

Answer: (2x + 3)(4x2 - 6x + 9)

Problem 7
Factoring by Grouping

Factor: 3x3 - 6x2 + 4x - 8

Solution

Step 1: Group terms in pairs

(3x3 - 6x2) + (4x - 8)

Step 2: Factor GCF from each group

3x2(x - 2) + 4(x - 2)

Step 3: Factor out common binomial

(x - 2)(3x2 + 4)

Answer: (x - 2)(3x2 + 4)

Note: 3x2 + 4 cannot be factored further over the real numbers

Problem 8
Difference of Cubes

Factor completely: 64x3 - 1

Solution

Step 1: Recognize as difference of cubes

64x3 - 1 = (4x)3 - 13

Step 2: Apply difference of cubes formula

a3 - b3 = (a - b)(a2 + ab + b2)

where a = 4x and b = 1

Step 3: Substitute

(4x - 1)[(4x)2 + (4x)(1) + 12]

(4x - 1)(16x2 + 4x + 1)

Answer: (4x - 1)(16x2 + 4x + 1)

Problem 9
Rational Root Theorem

Use the Rational Root Theorem to find all real zeros of f(x) = 2x3 - x2 - 13x - 6

Solution

Step 1: List potential rational zeros

p (factors of -6): ±1, ±2, ±3, ±6

q (factors of 2): ±1, ±2

Potential zeros: ±1, ±2, ±3, ±6, ±1/2, ±3/2

Step 2: Test x = -2

f(-2) = 2(-8) - 4 - 13(-2) - 6 = -16 - 4 + 26 - 6 = 0

Step 3: Synthetic division with x = -2

   -2 |  2   -1  -13   -6
      |      -4   10    6
      |___________________
         2   -5   -3    0

Quotient: 2x2 - 5x - 3

Step 4: Factor the quotient

2x2 - 5x - 3 = (2x + 1)(x - 3)

Step 5: Complete factorization

f(x) = (x + 2)(2x + 1)(x - 3)

All zeros: x = -2, x = -1/2, x = 3

Problem 10
Multi-Step Factoring

Factor completely: 2x4 - 162

Solution

Step 1: Factor out GCF

2x4 - 162 = 2(x4 - 81)

Step 2: Recognize difference of squares

x4 - 81 = (x2)2 - 92 = (x2 - 9)(x2 + 9)

Step 3: Factor x2 - 9 further (difference of squares)

x2 - 9 = (x - 3)(x + 3)

Step 4: Complete factorization

Answer: 2(x - 3)(x + 3)(x2 + 9)

Note: x2 + 9 cannot be factored over the real numbers

Section 3: Rational Functions (Problems 11-15)

Problem 11
Asymptotes

Find all vertical and horizontal asymptotes of f(x) = (3x2 - 12)/(x2 + x - 6)

Solution

Step 1: Factor numerator and denominator

Numerator: 3x2 - 12 = 3(x2 - 4) = 3(x - 2)(x + 2)

Denominator: x2 + x - 6 = (x + 3)(x - 2)

Step 2: Cancel common factors

f(x) = 3(x + 2)/(x + 3), x ≠ 2

Step 3: Find vertical asymptotes

Set remaining denominator = 0: x + 3 = 0

Vertical asymptote: x = -3

Step 4: Find horizontal asymptote

After cancellation: degree of numerator = 1, degree of denominator = 1

Leading coefficients: 3/1

Horizontal asymptote: y = 3

Note: x = 2 creates a hole, not a vertical asymptote

Problem 12
Holes

Find all holes in the graph of g(x) = (x2 + 5x + 6)/(x2 - 4)

Solution

Step 1: Factor completely

Numerator: x2 + 5x + 6 = (x + 2)(x + 3)

Denominator: x2 - 4 = (x - 2)(x + 2)

Step 2: Identify common factors

Common factor: (x + 2)

Step 3: Cancel common factor

g(x) = (x + 3)/(x - 2), x ≠ -2

Step 4: Find x-coordinate of hole

x + 2 = 0 → x = -2

Step 5: Find y-coordinate using simplified function

y = (-2 + 3)/(-2 - 2) = 1/(-4) = -1/4

Hole at: (-2, -1/4)

Vertical asymptote at: x = 2

Problem 13
Domain

Find the domain of h(x) = (x + 5)/(x2 - 2x - 15)

Solution

Step 1: Set denominator equal to zero

x2 - 2x - 15 = 0

Step 2: Factor

(x - 5)(x + 3) = 0

Step 3: Solve

x = 5 or x = -3

Step 4: State domain

Domain: All real numbers except x = -3 and x = 5

Interval notation: (-∞, -3) ∪ (-3, 5) ∪ (5, ∞)

Set notation: {x | x ≠ -3, x ≠ 5}

Problem 14
Complete Analysis

Find all asymptotes, holes, and intercepts of f(x) = (2x2 - 8)/(x2 + 3x + 2)

Solution

Step 1: Factor

Numerator: 2x2 - 8 = 2(x2 - 4) = 2(x - 2)(x + 2)

Denominator: x2 + 3x + 2 = (x + 1)(x + 2)

Step 2: Simplify

f(x) = 2(x - 2)/(x + 1), x ≠ -2

Step 3: Find hole

Hole at x = -2, y = 2(-2 - 2)/(-2 + 1) = 2(-4)/(-1) = 8

Hole: (-2, 8)

Step 4: Find vertical asymptote

x + 1 = 0 → x = -1

Vertical asymptote: x = -1

Step 5: Find horizontal asymptote

After simplification: degree 1/degree 1, coefficients 2/1

Horizontal asymptote: y = 2

Step 6: Find x-intercept (set numerator = 0)

2(x - 2) = 0 → x = 2

X-intercept: (2, 0)

Step 7: Find y-intercept (evaluate f(0))

f(0) = 2(0 - 2)/(0 + 1) = -4/1 = -4

Y-intercept: (0, -4)

Problem 15
Horizontal Asymptote

Determine the horizontal asymptote of f(x) = (5x3 - 2x + 1)/(3x3 + 7x2 - 4)

Solution

Step 1: Compare degrees

Degree of numerator: 3

Degree of denominator: 3

Degrees are equal

Step 2: Find ratio of leading coefficients

Leading coefficient of numerator: 5

Leading coefficient of denominator: 3

Ratio: 5/3

Horizontal asymptote: y = 5/3

Interpretation: As x → ±∞, f(x) → 5/3

Section 4: Inequalities (Problems 16-20)

Problem 16
Polynomial Inequality

Solve: x2 - 7x + 10 < 0

Solution

Step 1: Factor

x2 - 7x + 10 = (x - 2)(x - 5)

Step 2: Find critical values

x = 2 and x = 5

Step 3: Test intervals

Interval Test Point Sign
(-∞, 2) x = 0 (-)(-) = +
(2, 5) x = 3 (+)(-) = -
(5, ∞) x = 6 (+)(+) = +

Step 4: Select negative interval

We want f(x) < 0 (negative)

Solution: (2, 5)

Or: 2 < x < 5

Problem 17
Cubic Inequality

Solve: x3 + 2x2 - 3x ≥ 0

Solution

Step 1: Factor

x3 + 2x2 - 3x = x(x2 + 2x - 3) = x(x + 3)(x - 1)

Step 2: Find zeros

x = -3, 0, 1

Step 3: Create sign chart

Interval:  (-∞,-3) | (-3,0) | (0,1) | (1,∞)
Sign:         -    |   +    |   -   |   +

Step 4: We want f(x) ≥ 0 (positive or zero)

Positive intervals: (-3, 0) and (1, ∞)

Include boundaries (≥): x = -3, 0, 1

Solution: [-3, 0] ∪ [1, ∞)

Problem 18
Rational Inequality

Solve: (x - 4)/(x + 1) > 0

Solution

Step 1: Find critical values

Numerator = 0: x = 4

Denominator = 0: x = -1

Step 2: Test intervals

Interval Test Point Sign
(-∞, -1) x = -2 (-)/(-) = +
(-1, 4) x = 0 (-)/(+) = -
(4, ∞) x = 5 (+)/(+) = +

Step 3: Select positive intervals

We want f(x) > 0 (positive)

Do not include x = -1 (makes denominator zero)

Do not include x = 4 (strict inequality >)

Solution: (-∞, -1) ∪ (4, ∞)

Problem 19
Complex Rational Inequality

Solve: (x2 - 9)/(x - 1) ≤ 0

Solution

Step 1: Factor numerator

(x2 - 9)/(x - 1) = (x - 3)(x + 3)/(x - 1)

Step 2: Find critical values

From numerator: x = -3, 3

From denominator: x = 1

All critical values: -3, 1, 3

Step 3: Create sign chart

Interval:  (-∞,-3) | (-3,1) | (1,3) | (3,∞)
Sign:         -    |   +    |   -   |   +

Step 4: We want f(x) ≤ 0 (negative or zero)

Negative intervals: (-∞, -3) and (1, 3)

Include x = -3 and x = 3 (≤ and denominator ≠ 0)

Never include x = 1 (denominator = 0)

Solution: (-∞, -3] ∪ (1, 3]

Problem 20
Inequality with Multiplicity

Solve: x(x - 2)2(x + 1) > 0

Solution

Step 1: Identify zeros and multiplicities

x = 0 (multiplicity 1 - odd)

x = 2 (multiplicity 2 - even)

x = -1 (multiplicity 1 - odd)

Step 2: Key insight

Sign changes at odd multiplicity zeros (0 and -1)

Sign does NOT change at even multiplicity zero (2)

Step 3: Create sign chart

Interval:  (-∞,-1) | (-1,0) | (0,2) | (2,∞)
Factor x:      -   |   -    |   +   |   +
Factor(x-2)²:  +   |   +    |   +   |   +
Factor(x+1):   -   |   +    |   +   |   +
Product:       +   |   -    |   +   |   +

Step 4: Select positive intervals

We want f(x) > 0 (positive)

Positive intervals: (-∞, -1), (0, 2), and (2, ∞)

Note: (0, 2) and (2, ∞) can be combined as (0, ∞)

Solution: (-∞, -1) ∪ (0, ∞)

Or: x < -1 or x > 0

Practice Complete!

Congratulations on working through all 20 practice problems! You've covered all major topics from Module 3.

Next steps: Take the Module Quiz to test your understanding, then review the Study Guide to prepare for exams.

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