All categories

2 years ago

What is the value of the product (4 – 2i)(6 + 2i)? 20 – 4i 20 + 16i 28 + 16i 28 – 4i

Mathematics

2 answers:

Darya [45]2 years ago

8 0

(4 – 2i)(6 + 2i)

FOIL

First : 4*6 =24

Outer: 4*2i = 8i

Inner: -2i* 6 = -12i

Last: -2i*2i = -4i^2 =-4(-1) =4

Add together

24+8i-12i+4

28-4i

Answer: 28-4i

Ostrovityanka [42]2 years ago

5 0

Answer:

28-4i

Step-by-step explanation:

There for the answer is D

You might be interested in

Nicole is studying for her upcoming college entrance exams. She has already completed 20 practice problems and plans on completi

horsena [70]

Total number of problems Nicole will have completed: y
Number of nights she studies: x

She has already completed 20 practice problems:
When x=0, y=20

She plans on completing 6 more problems each night:
y=20+6x
y=6x+20

Please, see the attached graph.

Thanks.

8 0

1 year ago

A particular brand of tires claims that its deluxe tire averages at least 50,000 miles before it needs to be replaced. From past

Volgvan

Answer: We reject the null hypothesis, and we use Normal distribution for the test.

Step-by-step explanation:

Since we have given that

We claim that

Null hypothesis : $H_0:\mu\geq 50000$

Alternate hypothesis : $H_1:\mu$

There is 5% level of significance.

$\bar{X}=46800\\\\\sigma=9800\\\\n=29$

So, the test statistic would be

$z=\dfrac{\bar{X}-\mu}{\dfrac{\sigma}{\sqrt{n}}}\\\\z=\dfrac{46800-50000}{\dfrac{9800}{\sqrt{29}}}\\\\z=-1.75$

Since alternate hypothesis is left tailed test.

So, p-value = P(z≤-2.31)=0.0401

And the P-value =0.0401 is less than the given level of significance i.e. 5% 0.05.

So, we reject the null hypothesis, and we use Normal distribution for the test.

4 0

2 years ago

Which shows a recursive and an explicit formula for a sequence whose initial term is 14 and whose common difference is −4? A. A(

liberstina [14]

Answer: A. A(1) = 14; A(n) = (n − 1) −4; A(n) = 14 + (n − 1)(−4)

Step-by-step explanation:

Arithmetic sequence is a sequence that is identified by their common difference. Let a be the first term, n be the number of terms and d be the common difference.

For an arithmetic sequence, common difference 'd' is added to the preceding term to get its succeeding term. For example if a is the first term of a sequence, second term will be a+d, third term will give a+d+d and so on to generate sequence of the form,

a, a+d, a+3d, a+4d...

Notice that each new term keep increasing by a common difference 'd'

The nth term of the sequence Tn will therefore give Tn = a+(n-1)d

If the initial (first) term is 14 and common difference is -4, the nth of the sequence will be gotten by substituting a = 14 and d = -4 in the general formula to give;

Tn = 14+(n-1)-4 (which gives the required answer)

Tn = 14-4n+4

Tn = 18-4n

5 0

1 year ago

Read 2 more answers

Andre and Diego were each trying to solve 2x+6=3x−8. Describe the first step they each make to the equation. The result of Andre

Oksi-84 [34.3K]

Answer:

Andre subtracted 3x from both sides
Diego subtracted 2x from both sides

Step-by-step explanation:

Andre

Comparing the result of Andre's work with the original, we see that the "3x" term on the right is missing, and the x-term on the left is 3x less than it was. It is clear that Andre subtracted 3x from both sides of the equation.

Diego

Comparing the result of Diego's work with the original, we see that the "2x" term on the left is missing, and the x-term on the right is 2x less than it was. It is clear that Diego subtracted 2x from both sides of the equation.

_____

Comment on their work

IMO, Diego has the right idea, as his result leaves the x-term with a positive coefficient. He can add 8 and he's finished, having found that x=14.

Andre can subtract 6 to isolate the variable term, and that will give him -x=-14. This requires another step to get to x=14. Sometimes minus signs get lost, so this would not be my preferred sequence of steps.

As a rule, I like to add the opposite of the variable term with the least (most negative) coefficient. This results in the variable having a positive coefficient, making errors easier to avoid.

3 0

1 year ago

The volume of the sphere is StartFraction 500 Over 3 EndFractionπ cubic units. A sphere has a radius of x units. What is the val

Tpy6a [65]

Answer:

(b) Radius of the sphere = 5 units.

Step-by-step explanation:

Here, given:

The volume of the sphere = $(\frac{500}{3})\pi$ cubic units ... (1)

Also, radius of the sphere = x units

Now, VOLUME OF SPHERE = $(\frac{4}{3}) \pi r^3$

So, volume of a sphere with radius x = $(\frac{4}{3}) \pi (x)^3$

But volume of sphere is given by (1).

$\implies (\frac{500}{3})\pi = (\frac{4}{3}) \pi (x)^3\\\implies (\frac{500}{3}) = (\frac{4}{3}) (x)^3\\\implies x^3 = (\frac{500}{3}) \times (\frac{3}{4}) = 125\\\implies x^ 3 = 125 = (5)^3\\\implies x = 5$

Hence, radius of the sphere = 5 units.

4 0

2 years ago

Read 2 more answers