Algebra 7_4 Study Guide Factoring ax^2+bx+c - Watertown

Algebra 7-4 Study Guide: Factoring ax 2 + bx + c (pp 480-483 & 487)
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Attendance Problems.
Find each product.
1.(x – 2)(2x + 7)
2. (3y + 4)(2y + 9)
3. (3n – 5)(n – 7)
Factor each trinomial.
4. x2 +4x – 32
5. z2 + 15z + 36
6. h2 – 17h + 72
• I can factor quadratic trinomials of the form ax 2 + bx + c.
• I can use a graphing calculator to factor a polynomial by studying its
graph.
Common Core
CC.9-12.A.SSE.2 Use the structure of an expression to identify ways to rewrite it. For
example, see x4–y4 as (x2)2 - (y2)2, thus recognizing it as a difference of squares that
can be factored as (x2 – y2) (x2 + y2).
CC.9-12.A.SSE.3(a) Choose and produce an equivalent form of an expression to
reveal and explain properties of the quantity represented by the expression. a. Factor
a quadratic expression to reveal the zeros of the function it defines.
In the previous lesson you factored trinomials of the form x2 + bx + c. Now
you will factor trinomials of the form ax2 + bx + c, where a ≠ 0.
Algebra 7-4 Study Guide: Factoring ax 2 + bx + c (pp 480-483 & 487)
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When you multiply (3x + 2)(2x + 5), the coefficient of the x2-term is the
product of the coefficients of the x-terms. Also, the constant term in the
trinomial is the product of the constants in the binomials.
(3x + 2)(2x + 5) = 6x2 + 19x + 10
Video Example 1: Factor 6x2 + 19x + 10.
Guided Practice:
7. Factor 6x2 + 11x + 3
Algebra 7-4 Study Guide: Factoring ax 2 + bx + c (pp 480-483 & 487)
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Bob Shueh method to factor (with a leading coefficient.)
1.
2.
3.
4.
5.
Write the polynomial in standard form.
Use the distributive property to factor out a GCF.
Copy the first and last terms.
Multiply the first & last coefficients. Use this product in your “diamond.”
Rewrite the middle terms using the new diamond. If the two factors have opposite
signs, write the negative sign first.
6. Factor by grouping.
8. 3x2 – 2x – 8
Video Example 2: Factor.
A. 3x2 + 29x + 18
B. 7x 2 + 17x + 6
Algebra 7-4 Study Guide: Factoring ax 2 + bx + c (pp 480-483 & 487)
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Remember!
When b is negative and c is positive, the factors
of c are both negative.
Guided Practice: Factor the following.
9. 6x2 + 17x + 5
11. 3x2 + 13x + 12
10. 9x2 – 15x + 4
Algebra 7-4 Study Guide: Factoring ax 2 + bx + c (pp 480-483 & 487)
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Video Example 3: Factor the following:
A) 2x2 + 5x – 3
B) 3x2 - 10x – 8
Guided Practice: Factor each trinomial.
11.6x2 + 7x – 3
12. 4n2 – n – 3
When the leading coefficient is negative, factor out –1 from each term
before using other factoring methods.
Caution
When you factor out –1 in an early step, you
must carry it through the rest of the steps.
Algebra 7-4 Study Guide: Factoring ax 2 + bx + c (pp 480-483 & 487)
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Video Example 4: Factor –5x2 – 11x – 2
Guided Practice: Factor the following.
13. –6x2 – 17x – 12
14. –3x2 – 17x – 10
7-4 Assignment: (pp 484-485) 30, 35, 48, 50, 54, 58, 64, 65, 70-76.

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