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Math Coach Amy
Amy Ferguson Moncure

H Algebra 2/Trig · Unit 3

Sketch a Polynomial

Sketch the graph. Label the x- and y-intercepts.

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End Behavior

Even

x²
−x²

Odd

x³
−x³
What to Remember

Sketch from the factors

Write each x-intercept and its multiplicity.

State the degree and whether the leading coefficient is positive or negative. Use the matching end behavior above.

The y-intercept is the value when x = 0. Label the x-intercepts and the y-intercept on the sketch.

Level 1

Easy

Three intercepts, and the curve crosses at each one.

Example
Sketch the graph. Label the x- and y-intercepts.
y = (x + 2)(x − 1)(x − 4)

x = −2, Multiplicity 1

x = 1, Multiplicity 1

x = 4, Multiplicity 1

Degree 3, positive

x³

y-intercept when x = 0

y = (0 + 2)(0 − 1)(0 − 4) = 8

(−2, 0)(1, 0)(4, 0)y-intercept(0, 8)

Answer: y-intercept (0, 8)

1
Sketch the graph. Label the x- and y-intercepts.
y = (x + 4)(x + 1)(x − 2)
Show Answer

x = −4, Multiplicity 1

x = −1, Multiplicity 1

x = 2, Multiplicity 1

Degree 3, positive

x³

y-intercept when x = 0

y = (0 + 4)(0 + 1)(0 − 2) = −8

(−4, 0)(−1, 0)(2, 0)(0, −8)y-intercept

Answer: y-intercept (0, −8)

2
Sketch the graph. Label the x- and y-intercepts.
y = (x + 3)(x − 2)(x − 5)
Show Answer

x = −3, Multiplicity 1

x = 2, Multiplicity 1

x = 5, Multiplicity 1

Degree 3, positive

x³

y-intercept when x = 0

y = (0 + 3)(0 − 2)(0 − 5) = 30

(−3, 0)(2, 0)(5, 0)y-intercept(0, 30)

Answer: y-intercept (0, 30)

3
Sketch the graph. Label the x- and y-intercepts.
y = −(x + 5)(x + 2)(x − 1)
Show Answer

x = −5, Multiplicity 1

x = −2, Multiplicity 1

x = 1, Multiplicity 1

Degree 3, negative

−x³

y-intercept when x = 0

y = −(0 + 5)(0 + 2)(0 − 1) = 10

(−5, 0)(−2, 0)(1, 0)y-intercept(0, 10)

Answer: y-intercept (0, 10)

4
Sketch the graph. Label the x- and y-intercepts.
y = (x + 1)(x − 2)(x − 6)
Show Answer

x = −1, Multiplicity 1

x = 2, Multiplicity 1

x = 6, Multiplicity 1

Degree 3, positive

x³

y-intercept when x = 0

y = (0 + 1)(0 − 2)(0 − 6) = 12

(−1, 0)(2, 0)(6, 0)y-intercept(0, 12)

Answer: y-intercept (0, 12)

5
Sketch the graph. Label the x- and y-intercepts.
y = −(x + 3)(x − 1)(x − 4)
Show Answer

x = −3, Multiplicity 1

x = 1, Multiplicity 1

x = 4, Multiplicity 1

Degree 3, negative

−x³

y-intercept when x = 0

y = −(0 + 3)(0 − 1)(0 − 4) = −12

(−3, 0)(1, 0)(4, 0)(0, −12)y-intercept

Answer: y-intercept (0, −12)

Level 2

Medium

One intercept bounces.

Example
Sketch the graph. Label the x- and y-intercepts.
y = (x + 4)²(x − 1)(x − 3)

x = −4, Multiplicity 2

x = 1, Multiplicity 1

x = 3, Multiplicity 1

Degree 4, positive

x²

y-intercept when x = 0

y = (0 + 4)²(0 − 1)(0 − 3) = 48

(−4, 0)(1, 0)(3, 0)y-intercept(0, 48)

Answer: y-intercept (0, 48)

1
Sketch the graph. Label the x- and y-intercepts.
y = (x + 2)(x − 3)²(x − 6)
Show Answer

x = −2, Multiplicity 1

x = 3, Multiplicity 2

x = 6, Multiplicity 1

Degree 4, positive

x²

y-intercept when x = 0

y = (0 + 2)(0 − 3)²(0 − 6) = −108

(−2, 0)(3, 0)(6, 0)(0, −108)y-intercept

Answer: y-intercept (0, −108)

2
Sketch the graph. Label the x- and y-intercepts.
y = −(x + 5)²(x + 1)(x − 2)
Show Answer

x = −5, Multiplicity 2

x = −1, Multiplicity 1

x = 2, Multiplicity 1

Degree 4, negative

−x²

y-intercept when x = 0

y = −(0 + 5)²(0 + 1)(0 − 2) = 50

(−5, 0)(−1, 0)(2, 0)y-intercept(0, 50)

Answer: y-intercept (0, 50)

3
Sketch the graph. Label the x- and y-intercepts.
y = (x + 3)²(x − 2)(x − 4)
Show Answer

x = −3, Multiplicity 2

x = 2, Multiplicity 1

x = 4, Multiplicity 1

Degree 4, positive

x²

y-intercept when x = 0

y = (0 + 3)²(0 − 2)(0 − 4) = 72

(−3, 0)(2, 0)(4, 0)y-intercept(0, 72)

Answer: y-intercept (0, 72)

4
Sketch the graph. Label the x- and y-intercepts.
y = −(x + 1)(x − 2)²(x − 5)
Show Answer

x = −1, Multiplicity 1

x = 2, Multiplicity 2

x = 5, Multiplicity 1

Degree 4, negative

−x²

y-intercept when x = 0

y = −(0 + 1)(0 − 2)²(0 − 5) = 20

(−1, 0)(2, 0)(5, 0)y-intercept(0, 20)

Answer: y-intercept (0, 20)

5
Sketch the graph. Label the x- and y-intercepts.
y = (x + 6)²(x + 2)(x − 1)
Show Answer

x = −6, Multiplicity 2

x = −2, Multiplicity 1

x = 1, Multiplicity 1

Degree 4, positive

x²

y-intercept when x = 0

y = (0 + 6)²(0 + 2)(0 − 1) = −72

(−6, 0)(−2, 0)(1, 0)(0, −72)y-intercept

Answer: y-intercept (0, −72)

Level 3

Hard

Two bounces, or a fraction in front.

Example
Sketch the graph. Label the x- and y-intercepts.
y = (18)(x + 4)²(x − 1)²(x − 6)

x = −4, Multiplicity 2

x = 1, Multiplicity 2

x = 6, Multiplicity 1

Degree 5, positive

x³

y-intercept when x = 0

y = (18)(0 + 4)²(0 − 1)²(0 − 6) = −12

(−4, 0)(1, 0)(6, 0)(0, −12)y-intercept

Answer: y-intercept (0, −12)

1
Sketch the graph. Label the x- and y-intercepts.
y = (14)(x + 5)²(x − 2)²(x − 4)
Show Answer

x = −5, Multiplicity 2

x = 2, Multiplicity 2

x = 4, Multiplicity 1

Degree 5, positive

x³

y-intercept when x = 0

y = (14)(0 + 5)²(0 − 2)²(0 − 4) = −100

(−5, 0)(2, 0)(4, 0)(0, −100)y-intercept

Answer: y-intercept (0, −100)

2
Sketch the graph. Label the x- and y-intercepts.
y = −(15)(x + 3)²(x − 1)(x − 5)
Show Answer

x = −3, Multiplicity 2

x = 1, Multiplicity 1

x = 5, Multiplicity 1

Degree 4, negative

−x²

y-intercept when x = 0

y = −(15)(0 + 3)²(0 − 1)(0 − 5) = −9

(−3, 0)(1, 0)(5, 0)(0, −9)y-intercept

Answer: y-intercept (0, −9)

3
Sketch the graph. Label the x- and y-intercepts.
y = (16)(x + 2)²(x − 3)²
Show Answer

x = −2, Multiplicity 2

x = 3, Multiplicity 2

Degree 4, positive

x²

y-intercept when x = 0

y = (16)(0 + 2)²(0 − 3)² = 6

(−2, 0)(3, 0)y-intercept(0, 6)

Answer: y-intercept (0, 6)

4
Sketch the graph. Label the x- and y-intercepts.
y = −(18)(x + 6)²(x + 1)²(x − 2)
Show Answer

x = −6, Multiplicity 2

x = −1, Multiplicity 2

x = 2, Multiplicity 1

Degree 5, negative

−x³

y-intercept when x = 0

y = −(18)(0 + 6)²(0 + 1)²(0 − 2) = 9

(−6, 0)(−1, 0)(2, 0)y-intercept(0, 9)

Answer: y-intercept (0, 9)

5
Sketch the graph. Label the x- and y-intercepts.
y = (x + 3)³(x − 2)
Show Answer

x = −3, Multiplicity 3

x = 2, Multiplicity 1

Degree 4, positive

x²

y-intercept when x = 0

y = (0 + 3)³(0 − 2) = −54

(−3, 0)(2, 0)(0, −54)y-intercept

Answer: y-intercept (0, −54)

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