MA 1025 MOD 1 QUESTION 6-20

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Question1: Score 1/3

Classify the number as either positive or negative and as either rational or irrational. Does the number lie to the left or the right of  00 on the number line?

 

 −6.210735-6.210735 is

Your response

Correct response

positive

negative

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and

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Correct response

rational

rational

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. It lies to the

Your response

Correct response

right

left

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e. −6.210735-6.210735 is a terminating decimal so it is negative and rational. It lies to the left of 00.

Question2: Score 1/3

Classify the number as either positive or negative and as either rational or irrational. Does the number lie to the left or the right of  00 on the number line?

 5–√252 is

Your response

Correct response

negative

positive

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and

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Correct response

irrational

irrational

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. It lies to the 

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Correct response

left

right

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d. 5–√252 is positive and irrational. It lies to the right of 00.

Question3: Score 1/1

According to the U.S. Mint, the diameter of a dollar is 1.0431.043 inches. The circumference of the dollar would be the diameter multiplied by ππ.

 

Is the circumference of a dollar a whole number, a rational number, or an irrational number?

 

Your response

Correct response

Irrational Number

Feedback: Correct.

 

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The circumference of a dollar is 1.043π1.043π.  Since ππ is neither a whole number, nor a rational number, we conclude the circumference is an irrational number.

Question4: Score 1/1

Identify the number as rational, irrational, whole, or natural. Choose the answer that is the most descriptive.

 

−14−14

 

Your response

Correct response

Rational number

Feedback: Correct.

 

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The number −14−14 is a rational number.

Question5: Score 0/1

Identify the number as rational, irrational, whole, or natural. Choose the answer that is the most descriptive.

 

5–√5

 

Your response

Correct response

Natural number

Feedback: Incorrect.

Irrational number

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The number 5–√5 is an irrational number.

Question6: Score 0/1

In chemistry the volume for a certain gas is given by V=25TV=25T, where VV is measured in cc and TT is temperature in °C°C. If the temperature varies between 90°C90°C and 110°C110°C , find the set of volume values.

 

Enter the exact answer in interval notation.

 

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Do not enter any commas in your answer.

 

The range of the volume is  

Your response

Correct response

{x | 90≤x≤110} {x | 90≤x≤110}

[2250, 2750]

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We are given the volume for a certain gas, V=25TV=25T, and TT varies between 90°C90°C and 110°C110°C. We need to find the range of the volume.

 

Express the range of temperature as an inequality, and find the range for the volume.

 

 

 

90≤T≤11090≤T≤110

 

 

 

 

 

 

(25)90≤(25)T≤(25)1102590≤25T≤25110

 

 

 

Multiply by 2525.

 

 

2,250≤V≤2,7502,250≤V≤2,750

 

 

 

 

 

 

[2,250,2,750]2,250,2,750

 

 

 

Convert to interval notation.

 

Therefore, the range of the volume is [2,250,2,750]2,250,2,750.

Question7: Score 0/1

Describe all the xx-values within or including a distance of 44 units from the number 88.

 

Enter your answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

44 88

[4, 12]

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We want the distance between xx and 88 to be less than or equal to 44. We can draw a number line, such as in the figure below, to represent the condition to be satisfied.

 

44                                               44

A number line centered at 8 with a blue arrow of length 4 to the left and a red arrow of length 4 to the right. This shows the interval on which the condition is satisfied.

88   

 

The distance from xx to 88 can be represented using an absolute value symbol, |x−8|x−8. Write the values of xx that satisfy the condition as an absolute value inequality.

 

|x−8|≤4x−8≤4

 

We need to write two inequalities as there are always two solutions to an absolute value equation.

 

x−8x−8

 

 ≤4≤4

 

and

 

x−8x−8

 

 ≥−4≥−4

xx

 

 ≤12≤12

 

 

 

xx

 

 ≥4≥4

 

If the solution set is x≤12x≤12 and x≥4x≥4, then the solution set is an interval including all real numbers between and including 44 and 1212.

 

So |x−8|≤4x−8≤4 is equivalent to [4,12]4,12 in interval notation.

Question8: Score 0/1

Write the set in interval notation.

{x|−4<x≤8}x|−4<x≤8

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

-4 8

(-4, 8]

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Use a parentheses on the left of −4−4 and bracket after 88: (−4,8]−4,8.

Question9: Score 0/1

Solve the inequality involving absolute value.

 

|x+4|≥−9x+4≥−9

 

Enter the exact answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

{0

(-infinity, infinity)

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|x+4|x+4

 

 ≥−9≥−9

 

x+4x+4

 

 ≤9≤9

 

x+4x+4

 

 ≥−9≥−9

xx

 

 ≤5≤5

 

xx

 

 ≥−13≥−13

 

If the solution set is x≤5x≤5 and x≥−13x≥−13, then the solution set is an interval including all real numbers. So the solution set is (−∞,∞)−∞,∞.

Question10: Score 0/1

Solve the inequality.

 

4x−10≤64x−10≤6

 

Enter the exact answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

-0.17 0.25

(-infinity, 4]

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4x−104x−10

 

 ≤6≤6

 

 

4x4x

 

 ≤16≤16

 

 

(14)4x144x

 

 ≤16(14)≤1614

 

Multiply by 1414.

xx

 

 ≤4≤4

 

 

 

Express the inequality in interval notation.

(−∞,4]−∞,4

Question11: Score 0/1

Solve the inequality.

 

−4(x−1)+2>2x−3−3x−4x−1+2>2x−3−3x

 

Enter the exact answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

(-8, 0.25)

(-infinity, 3)

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−4(x−1)+2−4x−1+2

 

 >2x−3−3x>2x−3−3x

 

 

−4x+4+2−4x+4+2

 

 >−x−3>−x−3

 

 

−4x+6−4x+6

 

 >−x−3>−x−3

 

Collect like terms.

−3x−3x

 

 >−9>−9

 

Isolate the variable term.

xx

 

 <3<3

 

Dividing both sides by −3−3 reverses the inequality.

Express the inequality in interval notation.

(−∞,3)−∞,3

Question12: Score 0/1

Solve the inequality involving absolute value.

 

|x−3|+4≥10x−3+4≥10

 

Enter the exact answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

[0, 0.2]∪ [0.3, 0.9]

(-infinity, -3] U [9, infinity)

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|x−3|+4x−3+4

 

 ≥10≥10

|x−3|x−3

 

 ≥6≥6

 

x−3x−3

 

 ≤−6≤−6

 

x−3x−3

 

 ≥6≥6

xx

 

 ≤−3≤−3

 

xx

 

 ≥9≥9

 

Express the inequality in interval notation.

 

(−∞,−3]∪[9,∞)−∞,−3∪9,∞

Question13: Score 0/1

Solve the compound inequality.

 

2x−8<−142x−8<−14   or   7x+2≥97x+2≥9

 

Enter the exact answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

[−6,-1)∪ {0, 0}∪ (1,0.07}

(-infinity, -3) U [1, infinity)

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Solve both inequalities:

 

2x−82x−8

 

 <−14<−14

 

or

 

7x+27x+2

 

 ≥9≥9

2x2x

 

 <−6<−6

 

 

 

7x7x

 

 ≥7≥7

xx

 

 <−3<−3

 

 

 

xx

 

 ≥1≥1

 

Therefore, the solution set is x<−3x<−3 and x≥1x≥1 or in interval notation (−∞,−3)∪[1,∞)−∞,−3∪1,∞.

Question14: Score 0/1

Solve the equation for xx.

 

5x+5=3x−85x+5=3x−8

 

Enter the exact answer. Improper fractions are acceptable solutions. 

 

x=x=

 

 

Your response

Correct response

8/17

-13/2

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Apply standard algebraic operations.

 

5x+55x+5

 

 =3x−8=3x−8

 

 

5x+5−55x+5−5

 

 =3x−8−5=3x−8−5

 

Subtract 55 from both sides.

5x5x

 

 =3x−13=3x−13

 

Combine like terms.

2x2x

 

 =−13=−13

 

Place xx- terms on one side and simplify.

xx

 

 =−132=−132

 

Divide both sides by 22.

Question15: Score 0/1

Solve the equation for xx.

 

x+27−x−16=2x+27−x−16=2

Enter the exact answer.

 

x=x= 

Your response

Correct response

2

-65

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We have two denominators: 77 and 66. The LCD is 4242.

 

Next, multiply the whole equation (both sides of the equal sign) by 4242.

 

42(x+27−x−16)42x+27−x−16

 

 =(2)42=242

 

 

7⋅6(x+27)−7⋅6(x−16)7⋅6x+27−7⋅6x−16

 

 =84=84

 

Distribute 4242.

6(x+2)−7(x−1)6x+2−7x−1

 

 =84=84

 

Denominators cancel out.

6x+12−7x+76x+12−7x+7

 

 =84=84

 

Use the distributive property.

−x+19−x+19

 

 =84=84

 

Combine like terms.

−x−x

 

 =65=65

 

Subtract 1919 from both sides.

xx

 

 =−65=−65

 

Divide both sides by −1−1.

Question16: Score 0/1

Solve the equation for x.

 

4(x+3)−42=184x+3−42=18

 

x=x=  

Your response

Correct response

[0.0.5, 0.3]

12

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4(x+3)−424x+3−42

 

 =18=18

 

 

4(x+3)−42+424x+3−42+42

 

 =18+42=18+42

 

Add 4242 to both sides.

4(x+3)4x+3

 

 =60=60

 

 

4(x+3)44x+34

 

 =604=604

 

Divide both sides by 44.

x+3x+3

 

 =15=15

 

 

x+3−3x+3−3

 

 =15−3=15−3

 

Subtract 33 from both sides.

xx

 

 =12=12

 

 

Question17: Score 0/1

Solve for xx.

 

6(x+3)−27=x+66x+3−27=x+6

 

Enter the exact answer.

 

x=x= 

Your response

Correct response

0.03

3

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Apply standard algebraic properties.

 

6(x+3)−276x+3−27

 

 =x+6=x+6

 

 

6x+18−276x+18−27

 

 =x+6=x+6

 

Apply the distributive property.

6x−96x−9

 

 =x+6=x+6

 

Combine like terms.

5x5x

 

 =15=15

 

Place xx- terms on one side and simplify.

xx

 

 =155=155

 

Multiply both sides by 1515, the reciprocal of 55.

xx

 

 =3=3

 

 

Question18: Score 0/2

Solve for xx.

13+3x=141513+3x=1415

 

Enter the exact answer.

 

x=x= 

Your response

Correct response

46699.3

5

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State all xx-values that are excluded from the solution set.

 

The field below accepts a list  of numbers or formulas separated by semicolons (e.g. 2;4;62;4;6 or x+1;x−1x+1;x−1). The order of the list does not matter.

 

x≠x≠  

Your response

Correct response

0; 1415; 41513;141500

0

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Only one value is excluded from the solution set, 00. We have three denominators: 33, xx, and 1515. No factoring is required. The LCD is (3)(5)x35x.

 

Next, multiply the whole equation (both sides of the equal sign) by (3)(5)x35x.

 

(3)(5)x(13+3x)35x13+3x

 

 =(1415)(3)(5)x=141535x

(3)(5)x(13)+(3)(5)x(3x)35x13+35x3x

 

 =(1415)(3)(5)x=141535x

 

(5)x(1)+(3)(5)(3)5x1+353

 

 =(14)x=14x

 

Denominators cancel out.

5x+455x+45

 

 =14x=14x

 

 

9x9x

 

 =45=45

 

Collect like terms.

xx

 

 =459=459

 

Multiply by 1919, the reciprocal of 99.

xx

 

 =5=5

 

 

Question19: Score 0/1

Solve the inequality.

 

−3x+4>x−20−3x+4>x−20

 

Enter the exact answer in interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

(0, 0) U (∞)

(-infinity, 6)

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Solving this inequality is similar to solving an equation up until the last step.

 

−3x+4−3x+4

 

 >x−20>x−20

 

 

−4x+4−4x+4

 

 >−20>−20

 

Move variable terms to one side of the inequality.

−4x−4x

 

 >−24>−24

 

Isolate the variable term.

xx

 

 <6<6

 

Dividing both sides by −4−4 reverses the inequality.

 

The solution set is given by the interval (−∞,6)−∞,6.

Question20: Score 0/1

Solve the compound inequality.

 

−5<2x+3≤30−5<2x+3≤30

 

Enter the exact answer in interval notation. Improper fractions are acceptable in the interval notation.

 

To enter ∞∞, type infinity. To enter ∪∪, type U.

 

Your response

Correct response

(-4, 13.5) U [14, 35]

(-4,27/2]

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Leave the compound inequality intact, and perform solving procedures on the three parts at the same time.

 

−5−5

 

  <2x+3≤30<2x+3≤30

 

 

−8−8

 

 <2x≤27<2x≤27

 

Isolate the variable term, and subtract 33 from all three parts.

−4−4

 

 <x≤272<x≤272

 

Divide through all three parts by 22.

 

The solution set is given by the interval (−4,272]−4,272.

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