It takes Joey 1 hour to run 1 1/2 miles. How many miles does Joey run in 1 hour?

A store is having a sale in which all items are reduced by 20%. Including tax, Jennifer paid $21 for a pair of shorts. If the sa

Tju [1.3M]

Answer: the original price of the shorts was $25

Step-by-step explanation:

Let x represent the original price of the shorts.

The store is having a sale in which all items are reduced by 20%. This means that the amount of discount on the shorts is

20/100 × x = 0.2x

The price of the shorts would be

x - 0.2x = 0.8x

If the sales tax is 5%, then the amount of sales tax charged is

5/100 × 0.8x = 0.04x

The final cost of the shorts would be

0.8x + 0.04x = 0.84x

Including tax, Jennifer paid $21 for a pair of shorts. This means that

0.84x = 21

x = 21/0.84

x = 25

5 0

4 years ago

A 2-ft vertical post casts a 16-in. shadow at the same time a nearby cell phone tower casts a 120-ft shadow. How tall is the cel

Snowcat [4.5K]

Do 120÷8 aka 15 that is the answer

3 0

3 years ago

Explain why their are no solutions to the system of inequalities y ≤2x-5 y ≥2x+1

rosijanka [135]

Answer:

Sorry this is late and I think this is right.

They are both parallel, they have the same slope, and do not intersect. If you were to draw a slope out for it, you would find this to be true.

For example: Say the question called for you to explain why there aren't any solutions to these system of inequalities:

y < - 1/2x -3

y > 1/2x + 2

y= -x/2 -3 and y= -x/2 + 2 have the same exact slope, are parallel, and never intersect. The first line is 5 units below the second line when x = 0. Because the lines are parallel, it is always below the second line. The solutions of y < - x/2 -3 are the points in the plane below the first line. The solutions of y > 1/2 + 2 are points above the second line.

I hope this helps you. Good luck on whatever you're working on and stay safe! Please let me know if this helped you or didn't.

7 0

4 years ago

Name/ Uid:1. In this problem, try to write the equations of the given surface in the specified coordinates.(a) Write an equation

Gemiola [76]

To find:

(a) Equation for the sphere of radius 5 centered at the origin in cylindrical coordinates

(b) Equation for a cylinder of radius 1 centered at the origin and running parallel to the z-axis in spherical coordinates

Solution:

(a) The equation of a sphere with center at (a, b, c) & having a radius 'p' is given in cartesian coordinates as:

$(x-a)^{2}+(y-b)^{2}+(z-c)^{2}=p^{2}$

Here, it is given that the center of the sphere is at origin, i.e., at (0,0,0) & radius of the sphere is 5. That is, here we have,

$a=b=c=0,p=5$

That is, the equation of the sphere in cartesian coordinates is,

$(x-0)^{2}+(y-0)^{2}+(z-0)^{2}=5^{2}$

$\Rightarrow x^{2}+y^{2}+z^{2}=25$

Now, the cylindrical coordinate system is represented by $(r, \theta,z)$

The relation between cartesian and cylindrical coordinates is given by,

$x=rcos\theta,y=rsin\theta,z=z$

$r^{2}=x^{2}+y^{2},tan\theta=\frac{y}{x},z=z$

Thus, the obtained equation of the sphere in cartesian coordinates can be rewritten in cylindrical coordinates as,

$r^{2}+z^{2}=25$

This is the required equation of the given sphere in cylindrical coordinates.

(b) A cylinder is defined by the circle that gives the top and bottom faces or alternatively, the cross section, & it's axis. A cylinder running parallel to the z-axis has an axis that is parallel to the z-axis. The equation of such a cylinder is given by the equation of the circle of cross-section with the assumption that a point in 3 dimension lying on the cylinder has 'x' & 'y' values satisfying the equation of the circle & that 'z' can be any value.

That is, in cartesian coordinates, the equation of a cylinder running parallel to the z-axis having radius 'p' with center at (a, b) is given by,

$(x-a)^{2}+(y-b)^{2}=p^{2}$

Here, it is given that the center is at origin & radius is 1. That is, here, we have, $a=b=0,p=1$ . Then the equation of the cylinder in cartesian coordinates is,

$x^{2}+y^{2}=1$

Now, the spherical coordinate system is represented by $(\rho,\theta,\phi)$

The relation between cartesian and spherical coordinates is given by,

$x=\rho sin\phi cos\theta,y=\rho sin\phi sin\theta, z= \rho cos\phi$

Thus, the equation of the cylinder can be rewritten in spherical coordinates as,

$(\rho sin\phi cos\theta)^{2}+(\rho sin\phi sin\theta)^{2}=1$

$\Rightarrow \rho^{2} sin^{2}\phi cos^{2}\theta+\rho^{2} sin^{2}\phi sin^{2}\theta=1$

$\Rightarrow \rho^{2} sin^{2}\phi (cos^{2}\theta+sin^{2}\theta)=1$

$\Rightarrow \rho^{2} sin^{2}\phi=1$ (As $sin^{2}\theta+cos^{2}\theta=1$ )

Note that $\rho$ represents the distance of a point from the origin, which is always positive. $\phi$ represents the angle made by the line segment joining the point with z-axis. The range of $\phi$ is given as $0\leq \phi\leq \pi$ . We know that in this range the sine function is positive. Thus, we can say that $sin\phi$ is always positive.