MATHEMATICS HIGH SCHOOL

Please help!!Solve the equation and express each solution in a+bi form.
x^4-7x^2-8=0
a. x = -1, 1, 2 sqrt 2, or -2 sqrt 2
b. x = -i, i, 2 sqrt 2, or -2 sqrt 2
c. x = -1, 1, 2 sqrt 2i, or -2 sqrt 2i
d. x = -i, i, 2 sqrt 2i, or -2 sqrt 2i

Answers

Answer 1
Answer:

Because this is a fourth degree that will be tricky to factor as it is, we will do a u substitution. Let x^2=u. We can now rewrite that polynomial in terms of u: u^2-7u-8=0. Filling into the quadratic formula we have u=(7+/-√(49-4(1)(-8)))/(2). Simplifying down u=(7+/-√(81))/(2) and u=(7+9)/(2) or u=(7-9)/(2). That means that u = 8 or u = -1. But don't forget that we let u=x^2, so we have to put x-squared back in for u. That gives us x^2=8 which simplifies down to +/-2√(2). That also gives us x^2=-1. When we take the square root of -1, we have to use the fact that -1 = i^2, so we sub that in to get x=+/-i. All in all, your solutions are as follows: 2√(2),-2√(2),i,-i which is choice b.

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It should be " b " That should be right but u may want to wait for others to respond to this to make sure
I think it is B it cannot be the others!

How many ways can six kids line up in a single row to have their picture taken?

Answers

slot method aka permuations
6 slots
1st slot: 6 options
2nd slot: 5 options (1 went to first slot)
3rd slot: 4
4th slot:3
5th slot:2
6th slot:1

multiply
6*5*4*3*2*1=720

720 ways

Answer:

720

Step-by-step explanation:

A caterpillar is 2.83 centimeters long.how long I'd the caterpillar rounded to the nearest whole centimeter? A. 2 centimeters
B. 2.8 centimeters
C. 2.9 centimeters
D. 3 centimeters


I think it is D. but I am not sure. .........

Answers

The answer to this is D because a whole is a number without decimal points or fractions. And since it is over .5 , you round up. So 3 centimeters.
D. would be the correct answer because a "whole" number is one without decimals. Whole numbers are NOT negative, so any number 0 and above without a decimal place is a whole number.

When rounding, take decimal places that are 5 or greater and make them 10. You can think of it as adding 1 to the number to the left of the rounded decimal place.

ex.  1.5 rounds up to 2
        the 5 becomes a 10 which turns the 1 into a 2
ex.  5.6 rounds to 6
       the 6 rounds up to 10 making the 5 a 6
ex.  9.2 rounds to 9
       because 2 is less than five it rounds down to 0

The inner and outer Radii of a cylindrical pipe are 5 cm and 4 cm respectively. find the area of cross section of the pipe. 

Answers

To do this find the area of the inner pipe, and then find the area of the outer pipe, then subtract the larger of the two from the smaller, and that is the area of the cross section

Answer:

28.3 cm²

Step-by-step explanation:

You find the area of the whole section which is 5²π = 25π.

Then you find the area of the empty part which is 4²π = 16π.

Then you subtract to get 9π which is 28.27433388......

= 28.3 cm²

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Answers

Missing info:
Turkey Sizes: 
small - 2kg - 3.9kg 
medium - 4kg - 5.4kg 
large - 5.5kg - 7.2kg 
extra large - 7.3kg - 9.2kg 

Turkey Prices: 
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Large / Extra Large - £4.99 per kg 

3/4 lb x 14 persons = (3*14)/4 = 42/4 = 10.5 lbs

1 lb = 450 grams

10.5 lbs * 450grams/lb = 4,725 grams

1 kg = 1000 grams

4,725 grams * 1kg/1000 grams = 4725 kg / 1000 = 4.725 kg.

4.725 kg is under the Medium size of the Turkey.

Medium sized turkey costs £5.99 per kg.

4.725 kg * £5.99 per kg = £28.30

A turkey would cost  £28.30 for 14 people.

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Answers

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31 is the answer I think..
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