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2 years ago

Perform the indicated operation & simplify. Express the answer as a complex number. ( 6 − 7 i ) ( − 8 + 3 i ) =___

Mathematics

1 answer:

slega [8]2 years ago

6 0

( 6 − 7 i ) ( − 8 + 3 i )

First FOIL:

( 6 − 7 i ) ( − 8 + 3 i ) = -48 + 18i + 56i -21i^2

Combine like terms

= -48 + 74i -21i^2

Convert i^2 = -1

= -48 + 74i -21(-1)

And simplify

= -48 + 74i + 21

= -27 + 74i

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Evaluate S(3)=10+20log4(3+1)

dimulka [17.4K]

Asssuming you mean

evaluate $10+20log_4(3+1)$

remember $log_a(a)=1$
so
$10+20log_4(3+1)$ =
$10+20log_4(4)$ =
$10+20(1)$ =
10+20=
30

4 0

3 years ago

4% of _____ days is 56 days

schepotkina [342]

We have an equation: 56/? = 4/100

Cross multiply:
4*? = 56*100
⇒ ? = 56*100/4
⇒ ?= 1,400

4% of 1,400 days is 56 days~

4 0

3 years ago

Read 2 more answers

3. Solve the following application of a system of linear equations.

zhuklara [117]

Answer:

Equations:

$y = 14 + 9 x$ --- Cindy

$y = 10 x$ --- Ruben

Solution to equation:

Time they have the same amount: 14 minutes

Number of cards they have at that time: 140 flashcards

Step-by-step explanation:

Solving (a): Variables and what they represent

The variables to use are x and y

Where x represent the minutes and y represents the number of flashcards in x minutes

Solving (b): System of linear equation

Cindy:

$Existing\ Flashcards = 14$

$Additional = 9$ per minute

Total number of flashcards (y) in x minutes is:

$y = Existing\ Flashcards + Additional * x$

$y = 14 + 9 * x$

$y = 14 + 9 x$

Ruben:

$Rate = 10$ per minute

Total number of flashcards (y) in x minutes is:

$y = Rate * x$

$y = 10 * x$

$y = 10 x$

Solution to Equations:

Time they have the same amount.

To do this, we $equate$ $both$ expressions

i.e.

$10x = 14 + 9x$

Collect Like Terms

$10x - 9x = 14$

$x = 14$

Number of cards they have at that time.

Here, we simply substitute 14 for x in any of the equations.

$y = 10 x$

$y = 10 * 14$

$y = 140$

$y = 14 + 9 x$

$y = 14 + 9 * 14$

$y = 14 + 126$

$y = 140$

4 0

3 years ago

If x = -5 and y = x + 4, what ordered pair represents the solution? A. (5, -1) B. (-5, -1) C. (5, 1) D. (4, 4)

tekilochka [14]

B.) would be correct
(x,y)
x=-5
y=x+4
y=(-5)+4
y=-1
(-5,-1)

3 0

4 years ago

What is 3d+8=2d-7 is equations

fredd [130]

3d + 8 = 2d - 7 equals d = -15.

First, subtract 2d from both sides. Your problem should look like: 3d + 8 - 2d = -7.
Second, simplify 3d + 8 - 2d to get d + 8. Your problem should look like: d + 8 = -7.
Third, subtract 8 from both sides. Your problem should look like: d = -7 - 8.
Fourth, simplify -7 - 8 to get -15. Your problem should look like: d = -15, which is your answer.

Hopefully this helps, I'm not exactly sure what you meant by "is equations," but this is how you solve the problem.

6 0

3 years ago