While attempting to multiply the expression (2-5i)(5+2i) a student made a mistake.

(2-5i)(5+2i)= 10+4i -25i - 10i^2
=10+4(-1)-25(-1) - 10(1)
=10-4+25-10
=21
What is the error?

Answers

Answer 1

Answer:

The left side of the equation is ignored

i is treated as -1, which it is not, it is instead the square root of negative 1.

To solve it properly we get:

(2 - 5i)(5 + 2i)

= 10 + 4i - 25i - 10i²

= 10 + 21i + 10

= 20 - 21i

Answer 2

Answer:

The error is that, the student replaced i with -1 which is wrong as i = √-1

And he has replaced i^2 with 1 while i^2 = -1

Step-by-step explanation:

Given two numbers that are being multiplied are:

(2-5i)(5+2i)

We will solve the question to get the right result so that the error can be detected.

So, multiplying both

[tex]= 2(5+2i)-5i(5+2i)\\=10+4i-25i-10i^2\\=10-21i-10(-1)\ \ \ as\ i^2 = -1\\=10-21i+10[/tex]

The error is that, the student replaced i with -1 which is wrong as i = √-1

And he has replaced i^2 with 1 while i^2 = -1


Related Questions

Please help me with this question

Answers

Step-by-step explanation:

y-intercept in the point x = 0

B) is the easiest

g(x) or y value

g(x) = 3x² + 6x -9

= 3(0)² + 6(0) -9

= 0 + 0 -9

= -9

y-intercept = (0,-9)

Simplify (2/3)^3 (1/5 *2/3)^-3 (1/5)^4

Answers

Answer:

1/5

Step-by-step explanation:

im pretty sure thats it! and have a great day!

Answer:1/5 or 0.2

by-step explanation:

There are 13 girls on Janelle's soccer team. Uniforms cost $32 each. Which equation uses estimation correctly to show about how much money the team spent?

Answers

Answer:

$416

Step-by-step explanation:

From the above question,

Total number did people in a team = 13 girls

Uniform of each member of team = $32

The amount of money the team spent can be calculated as:

$32 × x

Where x = Number of people on the team = 13

The amount spent = $32 × 13

= $416

The amount the team spent is $416

Which postulate make the triangle congruent.?? help please

Answers

If you need help I can help you I did this before it’s q

Amelie and her friends pick 27 pounds of blueberries. Each pound of blueberries contains 195 blueberries. How many blueberries did Amelie and her friends pick?

Answers

Answer:

5,265 blueberries

Step-by-step explanation:

195 blueberries      1 pound

----------------------- x  --------------

          ?                     27 pounds

cancel the 1 pound

cross multiply the 195 and 27

Answer:

hi soo i just did this got it right and the correct answer is 5265.

Step-by-step explanation:

ik it might not help now but still work right? hehe

HElp PLZ DUE RIGHT KNaw

Answers

Answer:

variables :)

Step-by-step explanation:

Answer:

[tex]....8. \to \: b) \: \: 3 \\......................9. \to \: c) \: coefficients \\............... 10. \to \: d) \: variables[/tex]

what does m2+ m3= ???????????

Answers

Answer:

M2+m3=90

Step-by-step explanation:

Angle 1 already is equal to 90. A triangle can only go up to 180 wo the other two angles have to add up to 90.

Erica and Dana are collecting canned food to donate to a local charity. This morning, Dana had twice as many cans as Erica. Then Dana collected 8 more cans. If Dana has 42 cans of food. How many cans of food does Erica have? (Let e represent the number of cans of food Erica has).

Answers

Answer:

its 42÷2= 21 i think

Step-by-step explanation:

because dana has twice the nb of cans erica has so it dana has 48 then erica has the half number

Please help me find x

Answers

Answer:

x=13

Step-by-step explanation:

According to the question

3x+5x-14=90

8x-14=90

8x=90+14

8x=104

x=104/8

x=13

180 = 90 + 3x + 5x - 14
180 - 90 + 14 = 3x + 5x
104 = 8x
104/8 = x
x = 13

Checking:
3(13) + 90 + 5(13) - 14 = 180
180 = 180
So x=13

Solve for Angle Measures
What is the value of x in the figure?

X =

Answers

90-56 = 34 degrees!!!!!

Solve. What is the 15% of 15?

Answers

Answer:

2.25

Step-by-step explanation:

Step-by-step explanation:

It is 2.25

Lorelei knows that the mass of one dime is about 2.3 grams. She needs to find the mass of 4 dimes. Which equation shows how to use the Distributive Property to solve?

Answers

Answer:

Step-by-step explanation:

(4 × 2) + (4 × 0.3) = 9.2 grams

Ms. Lim asked her class to find an expression equivalent to 7 - 3 (4 - 2x) - 10x .

whats wrong with these problems? please include your work.

Answers

Answer:

Solving [tex]7-3(4-2x)-10x[/tex] we get [tex]-4x-5[/tex]

Step-by-step explanation:

Jon solved:

7-3(4-2x)-10x

4(4-2x)-10x

16-8x-10x

16-18x

Error in John Work

The error in John work is that he subtracted 7-3 first, which is wrong. According to the rule, first brackets are solved, then multiplication or division and then addition or subtraction is performed.

Madison Solved:

7-3(4-2x)-10x

7-3(2x)-10x

7-6x-10x

7-16x

Error in Madison Work

The error in Madison work is that she subtracted (4-2x) and get 2x which is wrong. Only like terms are added or subtracted. 4 and -2x are not like terms so, we can't subtract them

Selina Solved:

7-3(4-2x)-10x

7-12-2x-10x

-7-12x

Error in Selina Work

The error in Selina work is that she wrongly multiplied -3 with -2x

-3(-2x) we get 6x but Selina found it to be -2x which is wrong.

My solution:

Now, we will solve the equation correctly

[tex]7-3(4-2x)-10x[/tex]

First, multiply -3 with terms inside the bracket

[tex]7-12+6x-10x[/tex]

Now, combine like terms

[tex]7-12+6x-10x\\-5-4x[/tex]

or we can write -4x-5

So, solving [tex]7-3(4-2x)-10x[/tex] we get [tex]-4x-5[/tex]

Example:
Brigette is putting a border around a scrapbook cover.
The cover is 12 inches tall and 14.5 inches wide. How
much border does Brigette need?

Answers

Answer:

Step-by-step explanation:

Brigitte is putting a border, so she needs a perimeter

P=2(L+W)=2L+2W= 2*12+2*14.5=24+29=53

Sadie's sweets is having a sale on all their baked goods they are regularly priced at $4 but they are marked down to $2.6 what percent off are they​

Answers

Answer:

35% off

Step-by-step explanation:

= |4 - 2.6|/((4 + 2.6)/2) = 1.4/3.3 = 0.42424242424242 = 42.424242424242%

Percentage of decrease = |4 - 2.6|/4 = 1.4/4 = 0.35 = 35%

2.6 is a 35% decrease of 4.

35% off

Explanation: 30%= 0.30
4 times 0.30= 1.4
4-1.4= 2.6

you answered 6 out of 11 questions on your test. what is your score?​

Answers

Answer:

54

Step-by-step explanation:

.......................

Answer:

54

Step-by-step explanation:

2. If m is inversely proportional to n, the equation must be written as
C. n= km
m
A. k=
n
k
B.m=-
n
D. none of the above

Answers

Answer:

mn = k

Step-by-step explanation:

Given that,

m is inversely proportional to n.

ATQ,

[tex]m\propto \dfrac{1}{n}[/tex]

or

[tex]m=\dfrac{k}{n}[/tex]

Cross multiplying both sides,

mn = k

Hence, the required equation is "mn=k".

what's the answer to question c in the graph below

Answers

Answer:

3

Step-by-step explanation:

3is tha answer of pair of shoes..

am i rght

Answer:

3

Step-by-step explanation:

3 is right answer because it is largest pair of number

I need help please! ​

Answers

Answer/Step-by-step explanation:

Area of trapezium = ½*(AD + BC)*AB

Area = 42 cm²

AD = (x + 8) cm

BC = (x + 5) cm

AB = x cm

Plug in the values into the equation

42 = ½((x + 8) + (x + 5))*x

42 = ½((x + 8 + x + 5)*x

42 = ½(2x + 13)*x

Multiply both sides by 2

42*2 = (2x + 13)*x

84 = 2x² + 13x

2x² + 13x = 84

Subtract both sides by 84

2x² + 13x - 84 = 0

Three roads intersect to form a large triangular area as shown below.
-5 miles
300
What is the length, to the nearest tenth of a mile, of side x of the triangle?
O A. 2.5 miles
O B. 2.9 miles
O C. 4.0 miles
O D. 4.3 miles

Answers

Answer:

b i think

Step-by-step explanation:

I think your correct answer is B

What is the value of the expression?
3
131
3
152

Answers

Is there suppose to be a image before I don’t get it.

HAAALLLLPPPP plz

The production cost to make 10 shirts is modeled by the expression Syntax error from line 1 column 49 to line 1 column 73. Unexpected 'mathsize'. where y represents the number of meters of fabric needed to make the shirts. Which expression represents the production cost for one shirt?

Answers

Answer:

the second one, B

Step-by-step explanation:

This is because in both numbers the decimal was moved back one.

0.18y+55 is the  represents the production cost for one shirt.

What is Expression?

Expression is a combination of numbers, variables and operators.

Given that  production cost to make 10 shirts is modeled by the expression 1.8y+55.

The variable y represents the number of meters of fabric needed to make the shirts.

We need to find the expression represents the production cost for one shirt.

As there are 10 shirts so divide 1.8 with 10

we get 0.18.

And the value remains constant as it is a constant which does not change.

Hence, 0.18y+55 is the expression represents the production cost for one shirt.

To learn more on Expressions click:

https://brainly.com/question/14083225

#SPJ6

Which is the better value?

A. 6 ounces of hot Cheetos for $2.16
B. 10 ounces of hot Cheetos for $2.70

Answers

A. 6 ounces of hot cheetos

Answer:

B

Step-by-step explanation:

2.16/6 = 0.36 cents per 1 ounce

2.70/10 = 0.27 center per 1 ounce

Therefore B. 10 ounces of hot Cheetos for $2.70

What is 352 beats in 4 2/5 minutes please help and tell me step by step please

Answers

Answer:

352/4.4 =80

Got it?

Please give me Brainly

WILL GIVE BRAINLIEST
In the two-step equation below, what is the second step you would take to solve this equation?

3/4f+5=-5

a. Multiply both sides by 4/3
b. Add five to both sides.
c. Multiply by sides by 3/4
d. Subtract 5 from both sides.

Answers

Answer:

a. Multiply both sides by 4/3

Step-by-step explanation:

Since you're dealing with a fraction, multiplying both sides by the reciprocal, which is the fraction flipped, it could cancel out the fraction so now x is alone on one side.

Hope this helped! :)))

Can someone solve the joke please?

Why did the new boy steal a chair from the classroom?

Answers

Answer:

Because the teacher told him  to take a seat.

Answer:

Lol. Because the teacher told him to take a seat.

HELP PLEASE 35 points

Answers

Answer:

A because f(x) repeats

Step-by-step explanation:

Answer:

The answer is A

Step-by-step explanation:

hope it helps


Please Help Me
Find the premiter of the semi circle l. Round to the nearest hundredth ( use Pi key)​

Answers

Answer:

circumference of a circle = πd

π12 = 37.6991118

37.6991118/2 = 18.8495559

18.8495559 + 12 = 30.8495559

perimeter = 30.85

Plz help me get the right answer

Answers

Answer:

answerrrrrrrr

Step-by-step explanation:

-4x^2+10x+4

Help Please ! =(
Find the measures of the interior angles of the triangle.

Answers

x= 86
So, 86-35 which is 51.
A= 86 and C=51
Other Questions
In your own words, explain what are reflexive verbs and what do they describe. The Han Dynasty in China, the Gupta Empire in India, and the city-stateof Athens in Greece during their golden ages were known as eras of How did the englightment contribute to independence movements in Latin America What type of culture did Sparta have? Marine chemist exam in the mass percent composition of manganese sulfide compound from ocean floor he determined that 60.2% of this compound is sulfur determine the mole ratio between manganese and sulfur Perceptual skills can be enhancedbySelect one:a. Knowing and perceiving onself accuratelyb. Being empatheticc. Both are incorrectd. Both are correct= Both are correct Henry designs an experiment to find out why plants without flowers tend to be wind-pollinated and not animal-pollinated. He takes samples from a variety of plants and studies them in the field. He finds that the evidence supports his hypothesis. Which of these was the hypothesis Henry was testing? Choose the correct answer. Nonflowering plants make less pollen than flowering plants. Nonflowering plants lack the structures to attract animal pollinators. Nonflowering plants grow close to the ground and capture fewer pollinators. Nonflowering plants grow close to the ground because they have no pollen grains. Describe "Pax Romana" Let the x and y represent the tens digit and ones digit of a two digit number respectively. The sum of the digits of a two-digit number is 9. If the digits are reversed, the new number is 27 more than the original number. What is the original number? \cos (x-10\deg )=(\sqrt(3))/(2) I'm not sure how to find x PLS HELP ASAPWILL MARK BRAINLIEST Levi had 5 feet of warping paper.he used 1 feet to wrap a present how much paper dose Levi have left?HELP! Read the excerpt from "Daughter of Invention".Meanwhile, Yoyo was on her knees, weeping wildly, collecting all the little pieces of her speech, hoping that she could put it back together before the assembly tomorrow morning. But not even a sibyl could have made sense of those tiny scraps of paper. All hope was lost. "He broke it, he broke it," Yoyo moaned as she picked up a handful of pieces.What conflict does Yoyo face in this excerpt?Yoyo is frustrated by her inability to write a good speech for the assembly at her school.Yoyo is worried about insulting her teachers and peers with the speech she has written.Yoyo is saddened by her fathers disapproval of the message in her speech for the assembly.Yoyo is reminded of the terrors her father faced under the dictatorship of the Dominican Republic. How many moles are in 8.63 x 103 atoms of Li? Which of the following patterns best describes history of the Electronic Age from its beginning to the present day?A.electronic computer is invented > the Internet is used by the US Department of Defense > creation of the microprocessor > the Internet is used to meet business and personal needsB.creation of the microprocessor > electronic computer is invented > the Internet is used to meet business and personal needs > the Internet is used by the US Department of DefenseC.electronic computer is invented > creation of the microprocessor > the Internet is used by the US Department of Defense > the Internet is used to meet business and personal needsD.creation of the microprocessor > electronic computer is invented > the Internet is used by the US Department of Defense > the Internet is used to meet business and personal needs May someone please help me? This is due today and I'm confused. Form questions using inverse word order. put subject at the end. Pablo Dena en la cafetera List 3 ways a person can prevent from getting bacterial vaginosis? Select the correct literary form.A novel called Of Mice and Men.mythfictionlegend