AnswersCommon Core Algebra I 2014 - MA3109 B-CRSolving Quadratic Equations: Completing the Square

Solving Quadratic Equations: Completing the Square — Unit test Answers

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Which represents the solution(s) of the system of equations, y = x2 – 6x + 8 and y = –x + 4? Determine the solution set by graphing.

A
(1, 3) only
B
(2, 0) and (4, 0)
C
(1, 3) and (4, 0)
D
no solutions
22
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A rectangle’s width is 2 meters shorter than its length, l. Its area is 168 square meters. Which equation can be used to find the length of the rectangle?

A
l(l – 2) = 168
B
l(l + 2) = 168
C
2l 2 = 168
D
l 2 = 168
Option D
23

What are the solution(s) of the quadratic equation 98 – x2 = 0?

A
x =
Option A
B
x =
Option B
C
x =
Option C
D
no real solution
24

Which equations are true for x = –2 and x = 2? Select two optionsx2 – 4 = 0x2 = –4 3x2 + 12 = 04x2 = 162(x – 2)2 = 0

A
x2 – 4 = 0
B
x2 = –4
C
3x2 + 12 = 0
D
4x2 = 16
E
2(x – 2)2 = 0
25

Which are the roots of the quadratic function f(q) = q2 – 125? Select two options.q = 5q = -5q = 3q = -3q = 25

Question illustration
A
q = 5
Option A
B
q = -5
Option B
C
q = 3
Option C
D
q = -3
Option D
E
q = 25
Option E
26

What are the solutions to x2 + 8x + 7 = 0?

A
x = –8 and x = –7
B
x = –7 and x = –1
C
x = 1 and x = 7
D
x = 7 and x = 8
27

Brianna is graphing the function f(x) = x2 + 6x + 5. What x-intercepts should Brianna use to graph f(x)?

A
–5 and –1
B
–5 and 1
C
–1 and 5
D
1 and 5
28

Solve x2 – 8x = 3 by completing the square. Which is the solution set of the equation?

A
(4 minus StartRoot 19 EndRoot comma 4 + StartRoot 19 EndRoot)
Option A
B
(4 minus StartRoot 11 EndRoot comma 4 + StartRoot 11 EndRoot)
Option B
C
(4 minus StartRoot 8 EndRoot comma 4 + StartRoot 8 EndRoot)
Option C
D
(4 minus StartRoot 3 EndRoot comma 4 + StartRoot 3 EndRoot)
Option D
29

Which represents the solution(s) of the graphed system of equations, y = –x2 + x + 2 and y = –x + 3?

Question illustration
A
(1, 2)
B
(1, 2) and (0, 3)
C
(–1, 0) and (2, 0)
D
(2, 1)
30

What is the first step in solving the quadratic equation -5x2+8=133?

A
taking the square root of both sides of the equation
B
subtracting 8 from both sides of the equation
C
squaring both sides of the equation
D
adding 8 to both sides of the equation
31

Which represents the solution(s) of the graphed system of equations, y = x2 – 2x and y = –2x – 1?

Question illustration
A
(1, –1)
B
(0, 0) and (0, –1)
C
(0, 0) and (2, 0)
D
no solutions
32

Which equations can be used to find the lengths of the legs of the triangle? Select three options.

A
0.5(x)(x + 2) = 24
B
x(x + 2) = 24
C
x2 + 2x – 24 = 0
D
x2 + 2x – 48 = 0
E
x2 + (x + 2)2 = 100
33

A rectangle’s length is three times its width, w. Its area is 243 square units. Which equation can be used to find the width of the rectangle?

A
w2 = 3(243)
B
3w2 = 243
C
4w2 = 243
D
3w2 = 3(243)
34

What number should be added to both sides of the equation to complete the square? x2 – 10x = 7

Answer not available
35

What are the values of a, b, and c in the quadratic equation 0 = 5x – 4x2 – 2?

A
a = 5, b = 4, c = 2
B
a = 5, b = –4, c = –2
C
a = –4, b = 5, c = –2
D
a = 4, b = –5, c = –2
36

Rounded to the nearest hundredth, what is the positive solution to the quadratic equation 0=2x2+3x-8?Quadratic formula: x =

Question illustration
A
1.39
B
2.00
C
2.89
D
3.50
37

What are the solutions of the quadratic equation (x + 3)2 = 49?

A
x = –2 and x = –16
B
x = 2 and x =
Option B
C
x = 4 and x = –10
D
x = 40 and x = –58
38

The sum of a number and its square is 42. Which equation can be used to find the two numbers for which this is true?

A
x2 + x = 42
B
x2 + 2x = 42
C
x2 + x + 42 = 0
D
x2 + 2x + 42 = 0
39

Which shows the correct substitution of the values a, b, and c from the equation 0 = 4x2 + 2x – 1 into the quadratic formula below?Quadratic formula: x =

Question illustration
A
x = StartFraction negative 2 plus or minus StartRoot 2 squared minus 4(4)(negative 1) EndRoot Over 2(4) EndFraction
Option A
B
x = StartFraction negative 2 plus or minus StartRoot 2 squared minus 4(4)(1) EndRoot Over 2(4) EndFraction
Option B
C
x = StartFraction negative 2 plus or minus StartRoot 2 squared + 4(4)(negative 1) EndRoot Over 2(4) EndFraction
Option C
D
x = StartFraction negative 2 plus or minus StartRoot negative 2 squared minus 4(4)(negative 1) EndRoot Over 2(4) EndFraction
Option D
40

Ramiya is using the quadratic formula to solve a quadratic equation. Her equation is x = after substituting the values of a, b, and c into the formula. Which is Ramiya’s quadratic equation?Quadratic formula: x =

Question illustration
A
0 = x2 + 3x + 2
B
0 = x2 – 3x + 2
C
0 = 2x2 + 3x + 1
D
0 = 2x2 – 3x + 1

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