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3 years ago

Which are the solutions of the quadratic equation x2 =-5-3

Mathematics

1 answer:

alexdok [17]3 years ago

5 0

Answer: x = 2 • ± √2 = ± 2.8284

Step-by-step explanation:

Theory : A difference of two perfect squares, A2 - B2 can be factored into (A+B) • (A-B)

Proof : (A+B) • (A-B) =

A2 - AB + BA - B2 =

A2 - AB + AB - B2 =

A2 - B2

Note : AB = BA is the commutative property of multiplication.

Note : - AB + AB equals zero and is therefore eliminated from the expression.

Check : 8 is not a square !!

Ruling : Binomial can not be factored as the difference of two perfect squares.

Equation at the end of step 1 :

x2 - 8 = 0

Step 2 :

Solving a Single Variable Equation :

2.1 Solve : x2-8 = 0

Add 8 to both sides of the equation :

x2 = 8

When two things are equal, their square roots are equal. Taking the square root of the two sides of the equation we get:

x = ± √ 8

Can √ 8 be simplified ?

Yes! The prime factorization of 8 is

2•2•2

To be able to remove something from under the radical, there have to be 2 instances of it (because we are taking a square i.e. second root).

√ 8 = √ 2•2•2 =

± 2 • √ 2

The equation has two real solutions

These solutions are x = 2 • ± √2 = ± 2.8284

Two solutions were found :

x = 2 • ± √2 = ± 2.8284

Not sure what you need help with, but I hope I helped you somehow.

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10 black balls and 5 white balls are placed in an urn. Two balls are then drawn in succession. What is the probability that the

Alex787 [66]

Answer:

The probability that the second ball drawn is a white ball if the second ball is drawn without replacing the first ball is $\frac{1}{3}$ or 0.3333

Step-by-step explanation:

Probability is the greater or lesser possibility that a certain event will occur. In other words, the probability establishes a relationship between the number of favorable events and the total number of possible events. Then, the probability of any event A is defined as the ratio between the number of favorable cases (number of cases in which event A may or may not occur) and the total number of possible cases. This is called Laplace's Law:

$P(A)\frac{number of favorable cases of A}{total number of possible cases}$

Each of the results obtained when conducting an experiment is called an elementary event. The set of all elementary events obtained is called the sample space, so that every subset of the sample space is an event.

The total number of possible cases is 15 (10 black balls added to the 5 white balls).

As each extraction is without replacement, the events are dependent. For that, the dependent probabilities are defined first

Two events are dependent on each other when the fact that one of them is verified influences the probability of the other being verified. In other words, the probability of A happening is affected because B has happened or not.

The probability of two events A and B of two successive simple experiments in a dependent compound experiment is:

A and B are dependent ⇔ P (A ∩ B) = P (A) · P (B / A)

P (A ∩ B) = P (B) · P (B / A)

As the color of the first ball that is extracted is unknown, there are two cases: that the ball is black or that the ball is white.

It will be assumed first that the first ball drawn is black. Then the probability of this happening is $\frac{10}{15}$ since the number of black balls in the urn is 10 and the total number of cases is 15. It is now known that the second ball extracted will be white. Then the number of favorable cases will be 5 (number of white balls inside the ballot urn), but now the number of total cases is 14, because a ball was previously removed that was not replaced. So the probability of this happening is $\frac{5}{14}$

So the probability that the first ball is black and the second white is:

$\frac{10}{15} *\frac{5}{14} =\frac{5}{21}$

It will now be assumed first that the first ball that is drawn is white. Then the probability of this happening is $\frac{5}{15}$ since the number of white balls in the urn is 5 and the total number of cases is 15. And it is known that the second ball drawn will be white. Then, the number of favorable cases will be 4 (number of white balls inside the urn, because when removing a white ball and not replacing it, its quantity will decrease), and the total number of cases is 14, same as in the previous case So, the probability of this happening is $\frac{4}{14}$

So the probability that the first ball is white and the second white is:

$\frac{5}{15} *\frac{4}{14} =\frac{2}{21}$

If A and B are two incompatible events, that is, they cannot occur at the same time, the probability of occurrence A or of occurrence B will be the sum of the probabilities of each event occurring separately.

These are events are incompatible, since I cannot, in a first extraction, extract a black and white ball at the same time. So:

$\frac{5}{21} +\frac{2}{21} =\frac{7}{21}=\frac{1}{3} =0.3333$

Finally, the probability that the second ball drawn is a white ball if the second ball is drawn without replacing the first ball is $\frac{1}{3}$ or 0.3333

3 0

3 years ago

Solve y ' ' + 4 y = 0 , y ( 0 ) = 2 , y ' ( 0 ) = 2 The resulting oscillation will have Amplitude: Period: If your solution is A

Vlad [161]

Answer:

$y(x)=sin(2x)+2cos(2x)$

Step-by-step explanation:

$y''+4y=0$

This is a homogeneous linear equation. So, assume a solution will be proportional to:

$e^{\lambda x} \\\\for\hspace{3}some\hspace{3}constant\hspace{3}\lambda$

Now, substitute $y(x)=e^{\lambda x}$ into the differential equation:

$\frac{d^2}{dx^2} (e^{\lambda x} ) +4e^{\lambda x} =0$

Using the characteristic equation:

$\lambda ^2 e^{\lambda x} + 4e^{\lambda x} =0$

Factor out $e^{\lambda x}$

$e^{\lambda x}(\lambda ^2 +4) =0$

Where:

$e^{\lambda x} \neq 0\\\\for\hspace{3}any\hspace{3}\lambda$

Therefore the zeros must come from the polynomial:

$\lambda^2+4 =0$

Solving for $\lambda$ :

$\lambda =\pm2i$

These roots give the next solutions:

$y_1(x)=c_1 e^{2ix} \\\\and\\\\y_2(x)=c_2 e^{-2ix}$

Where $c_1$ and $c_2$ are arbitrary constants. Now, the general solution is the sum of the previous solutions:

$y(x)=c_1 e^{2ix} +c_2 e^{-2ix}$

Using Euler's identity:

$e^{\alpha +i\beta} =e^{\alpha} cos(\beta)+ie^{\alpha} sin(\beta)$

$y(x)=c_1 (cos(2x)+isin(2x))+c_2(cos(2x)-isin(2x))\\\\Regroup\\\\y(x)=(c_1+c_2)cos(2x) +i(c_1-c_2)sin(2x)\\$

Redefine:

$i(c_1-c_2)=c_1\\\\c_1+c_2=c_2$

Since these are arbitrary constants

$y(x)=c_1sin(2x)+c_2cos(2x)$

Now, let's find its derivative in order to find $c_1$ and $c_2$

$y'(x)=2c_1 cos(2x)-2c_2sin(2x)$

Evaluating $y(0)=2$ :

$y(0)=2=c_1sin(0)+c_2cos(0)\\\\2=c_2$

Evaluating $y'(0)=2$ :

$y'(0)=2=2c_1cos(0)-2c_2sin(0)\\\\2=2c_1\\\\c_1=1$

Finally, the solution is given by:

$y(x)=sin(2x)+2cos(2x)$

5 0

3 years ago

(8.218+9.93)+(17.782+0.07)

Licemer1 [7]

First, using the order of operations(PEMDAS), you would solve what is inside the parenthesis.
(8.218 + 9.93) + (17.782 + 0.07)
(18.148) + (17.852)
18.148 + 17.852

Now, all you would have to do is add the two sums.
18.148 + 17.852 = 36

The answer would be 36.

I hope this helps!

5 0

3 years ago

Hello! Please help.

valina [46]

1 -

3 cups left.

David biked a total of 158 miles (option C)

Why?

- First exercise:

To solve the problem we need to consider that for each 1/2 cup of cornmeal, we will have 6 corn muffins.

So, calculating we have:

$TotalMuffins=24=4*6\\\\UsedCups=\frac{1}{2}*4=2Cups$

We can see that, if each 1/2 cups can give us 6 corn muffins, 2 cups can give us 24 corn muffins.

$CupsLeft=5cups-2cups=3cups$

Hence, there are 3 cups left.

- Second exercise:

We can solve the problem by multiplying or adding the fractions according to the number of dots assigned to each one.

So, calculating we have:

$FirstDay=10miles*2=20miles\\SecondDay=10\frac{1}{2}miles=10.5miles\\ThirdDay=11miles*3=33miles\\FourthDay=11\frac{1}{2}miles*4=11.5miles*4=46miles\\FifthDay=12miles*3=36miles\\SixthDay=12\frac{1}{2}miles=12.5miles$

$Total=20miles+10.5miles+33miles+46miles+36miles+12.5miles\\Total=158miles$

Hence, we have that David covered a total 158 miles. (Option C)

Have a nice day!

5 0

3 years ago

Read 2 more answers

Just need the answer

sveta [45]

Answer:

the pic is black send another one

4 0

3 years ago