Select the equivalent expression

Solve the following equation:

Rama09 [41]

Complete the square.

$z^4 + z^2 - i\sqrt 3 = \left(z^2 + \dfrac12\right)^2 - \dfrac14 - i\sqrt3 = 0$

$\left(z^2 + \dfrac12\right)^2 = \dfrac{1 + 4\sqrt3\,i}4$

Use de Moivre's theorem to compute the square roots of the right side.

$w = \dfrac{1 + 4\sqrt3\,i}4 = \dfrac74 \exp\left(i \tan^{-1}(4\sqrt3)\right)$

$\implies w^{1/2} = \pm \dfrac{\sqrt7}2 \exp\left(\dfrac i2 \tan^{-1}(4\sqrt3)\right) = \pm \dfrac{2+\sqrt3\,i}2$

Now, taking square roots on both sides, we have

$z^2 + \dfrac12 = \pm w^{1/2}$

$z^2 = \dfrac{1+\sqrt3\,i}2 \text{ or } z^2 = -\dfrac{3+\sqrt3\,i}2$

Use de Moivre's theorem again to take square roots on both sides.

$w_1 = \dfrac{1+\sqrt3\,i}2 = \exp\left(i\dfrac\pi3\right)$

$\implies z = {w_1}^{1/2} = \pm \exp\left(i\dfrac\pi6\right) = \boxed{\pm \dfrac{\sqrt3 + i}2}$

$w_2 = -\dfrac{3+\sqrt3\,i}2 = \sqrt3 \, \exp\left(-i \dfrac{5\pi}6\right)$

$\implies z = {w_2}^{1/2} = \boxed{\pm \sqrt[4]{3} \, \exp\left(-i\dfrac{5\pi}{12}\right)}$

3 0

1 year ago

Ya'll please help me!!!!. The water was pumped out of a backyard pond, What is the domain of this graph????

saw5 [17]

Stuck on the same question and it looks like nobody cares to answer on this website

6 0

3 years ago

Read 2 more answers

Writing equivalent ratios and ordered pairs Gallons 1 2 3 Quarts 4 8 12 which ordered pairs represents the equivalent ratios in

Sphinxa [80]

Step-by-step explanation:

gallons to quarts have the ratio 1:4.

there are 4 quarts in a gallon (hence the name of quarts by the way).

so, the question is really, which order pair have also a 1:4 ratio between x and y ?

(1, 4)

(2, 8)

(3, 12)

the (4, 1) would represent a 4:1 ratio.

and as you know, 4/1 is different to 1/4.

a ratio is nothing else than a fraction. just the "whole" is different.

the pure fraction 1/4 means that the whole is 4/4, has 4 times 1/4.

a ratio 1:4 (you can also write as 1/4) means that the whole has 5 (1+4) parts.

other than that they are compared and calculated with the same way as normal fractions.

4 0

2 years ago

A fuel pump at a gasoline station doesn't always dispense the exact amount displayed on the meter. When the meter reads 1.000 L,

pogonyaev

Answer:

P(X > 1.05) = 1 - 0.8413 = 0.1587 = 15.87%.

Step-by-step explanation:

Problems of normally distributed samples can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

In this problem, we have that:

$\mu = 1, \sigma = 0.05$