AnswersFL-1200710-Mathematics for College Algebra ASolving Quadratic Equations: Quadratic Formula

Solving Quadratic Equations: Quadratic Formula — Unit test Answers

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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
2
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Solve x2 = 12x – 15 by completing the square. Which is the solution set of the equation?

A
(negative 6 minus StartRoot 51 EndRoot comma negative 6 + StartRoot 51 EndRoot)
Option A
B
(negative 6 minus StartRoot 21 EndRoot comma negative 6 + StartRoot 21 EndRoot)
Option B
C
(6 minus StartRoot 51 EndRoot comma 6 + StartRoot 51 EndRoot)
Option C
D
(6 minus StartRoot 21 EndRoot comma 6 + StartRoot 21 EndRoot)
Option D
3

Zacharias is using the quadratic formula to solve the equation 0 = –2x2 + 5x – 3. He begins by substituting as shown.Quadratic formula: x = Substitution:

Question illustration
A
The –5 should be 5.
B
The 52 should be –52.
C
The 2 in the numerator should be –2.
D
The 2 in the denominator should be –2.
4

What number should be added to both sides of the equation to complete the square? x2 + 12x = 11

Answer not available
5

A rectangle has an area of 40 square units. The length is 6 units greater than the width.

A
8 by 5
B
10 by 4
C
11 by 9
D
13 by 7
6

Isoke is solving the quadratic equation by completing the square.10x2+40x-13=010x2+40x=13A(x2+4x)=13

A
-13
B
4
C
10
D
40
7

What is the solution to 2x2+8x=x2-16?

A
x=-4
B
x=-2
C
x=2
D
x=4
8

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
9

What are the zeros of the function f(x) = x2 + 5x + 5 written in simplest radical form?Quadratic formula: x =

Question illustration
A
x =
Option A
B
x =
Option B
C
x =
Option C
D
x =
Option D
10

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
11

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
12

A function g(x) has x-intercepts at (, 0) and (6, 0). Which could be g(x)?

Question illustration
A
g(x) = 2(x + 1)(x + 6)
B
g(x) = (x – 6)(2x – 1)
C
g(x) = 2(x – 2)(x – 6)
D
g(x) = (x + 6)(x + 2)
13

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
14

Use the graph of the quadratic function y = x2 + x + 4 to answer the question.

Question illustration
A
–2 and 4
B
4 and 0
C
4 and –4
D
–8 and –4
15

Which is a zero of the quadratic function f(x) = 9x2 – 54x – 19?

A
x =
Option A
B
x = 3
Option B
C
x = 6
Option C
D
x = 9
Option D
16

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
17

Alessandro wrote the quadratic equation in standard form. What is the value of c in his new equation?

Question illustration
A
Option
Option A
B
Option
Option B
C
Option
Option C
D
Option
Option D
18

Consider the graph of the quadratic function y = –2(x + 2)2 – 1 with no real zeros. What number can be added to the right side of the equation to change it to a function with one real root?

Answer not available
19

The first three steps for solving the quadratic equation by completing the square are shown. Fill in the missing number in the last step. 9x2 +54x = 7 9(x2 + 6x) = 7 9(x2 + 6x + 9) = 7 +

Answer not available
20

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

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