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sdas [7]
3 years ago
7

A student multiplies (4+5i) (3-2i) incorrectly and obtains 12-10i what is the students mistakes

Mathematics
1 answer:
Rufina [12.5K]3 years ago
4 0

Answer:

1. In the multiplication of the imaginary parts, the student forgot to square of i. OR

2. The student has only multiplied the real parts and the imaginary parts.

Correct value =22+7i.

Step-by-step explanation:

The given expression is

(4+5i)(3-2i)

A student multiplies (4+5i) (3-2i) incorrectly and obtains 12-10i.

Student's mistake can be either 1 or second:

1. In the multiplication of the imaginary parts, the student forgot to square of i.

2. The student has only multiplied the real parts and the imaginary parts.

(4+5i)(3-2i)=4\times 3+5\times (-2)i=12-10i

Which is not correct. The correct steps are shown below.

Using distributive property, we get

4(3-2i)+5i(3-2i)

4(3)+4(-2i)+5i(3)+5i(-2i)

12-8i+15i-10i^2

12+7i-10(-1)       [\because i^2=-1]

12+7i+10

22+7i

Therefore, the correct value of (4+5i)(3-2i) is 22+7i.

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Fynjy0 [20]

Answer:

(-7, -10)

x=-7\\y=-10

Step-by-step explanation:

4x-4y=12

Substitute x for -7.

4(-7)-4y=12

Multiply 4 by -7.

-28-4y=12

Add 28 on both sides.

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Divide -4 on both sides.

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4 0
3 years ago
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mr_godi [17]

Answer:

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Step-by-step explanation:

Let us assume that the Ella's Normal hourly pay = $x per hour

Over hourly pay = 1.5 times ( Normal pay)

                           = 1.5 ( x)  =  $ 1.5 x

⇒Ella earns $1.5x in 1 hour of overtime.

So the amount she earns in 4 hour of overtime =  4 times (per hour pay)

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The amount Ella earned in 4 hours of over time = $72.00

According to the question:

$ 6 x  = $72.00

or, x = 72/6

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or , x  =  $12

Hence, Ella's normal hourly pay is $12 per hour.

7 0
3 years ago
A book costs $ 25.Marilyn bought the book during a sale 15% discount. How much did she pay for the book
blondinia [14]
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~theLocoCoco

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The slope of the line below is -3. Use the coordinates of the labeled point to find the point-slope equation of the line.
muminat
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