Algebra 1 Common Core Student Edition, Grade 8-9

(Marvins-Underground-K-12) #1
Go t I t? 4. Suppose the total area of the garden and border in Problem 4 is 150 ft2. What
is the side length x of each square plot? Round to the nearest hundredth.

9 Lesso n Ch eck^


Do y o u k n o w H OW?
Solve each equation by completing the square.
1. x2 + 8x = 180


  1. f 2 — 4t — 165 = 0

  2. m2 + 7m — 294 = 0

  3. 2z2 + 3z = 135


MATHEMATICAL
Do y o u UN DERSTAND? ^PRACTICES


  1. Vocabulary Tell whether you would use square roots,
    factoring, or completing the square to solve each
    equation. Explain your choice of method.
    a. k2 - 3k = 304 b. f2- 61+16 = 0

  2. C o m p a r e a n d C o n t r a s t How is solving a quadratic
    equation using square roots like completing the
    square? How is it different?


Pr act i ce an d Pr o b l em - So l v i n g Ex er ci ses


Practice Find the value of c such that each expression is a perfect-square trinomial. See Problem 1.


  1. x2+18x+c 8. z2 + 2 2z + c 9. p2 - 30p + c

  2. k2 — 5k + c 11. g 2 + 17g+ c 12. q2 — 4q + c


MATHEMATICAL
PRACTICES

Solve each equation by completing the square. If necessary, round to the
nearest hundredth.

See Problem 2.


  1. g2 + 7g = 144
    16. a2 - 2a - 35 = 0
    14. r2 - 4r = 30
    17. m2+ 12 m+ 19 = 0


Find the vertex of each parabola by completing the square.


  1. y = x2 + 4 x - 16 20. y = x2 + 18x — 3 0 7

  2. y = x2 + 6x-7 23. y = x2 + 2x - 28

  3. m2 + 16 m = -59

  4. w2 - Uw + 13 = 0


See Problem 3.


  1. y = x2 — 2x — 323

  2. y = x2 + 12x - 468


Solve each equation by completing the square. If necessary, round to the
nearest hundredth.

See Problem 4.


  1. 4a2 — 8a = 24
    28. 4w2 + 12u;-44 = 0
    26. 2y2 - 8y - 10 = 0
    29. 3r2 + 18r = 21
    27. 5n2 — 3n — 1 5 = 1 0
    30. 2v2 — 10u — 20 = 8
    31. Art The painting shown at the right has an area of
    420 in.2. What is the value of x? x in.


(2x + 5) in.

L


PowerAlgebra.com ^ Lesson 9-5 Completing the Square^
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