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3 years ago

Check my work? Rational and irrational numbers.

Mathematics

2 answers:

Sauron [17]3 years ago

3 0

Here, Rational numbers are: = 2/9 and √225
& other two are irrational

Hope this helps!

telo118 [61]3 years ago

3 0

43 is the asnwer hope it helped

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A rock thrown vertically upward from the surface of the moon at a velocity of 36m/sec reaches a height of s = 36t - 0.8 t^2 met

Verdich [7]

Answer:

a. The rock's velocity is $v(t)=36-1.6t \:{(m/s)}$ and the acceleration is $a(t)=-1.6 \:{(m/s^2)}$

b. It takes 22.5 seconds to reach the highest point.

c. The rock goes up to 405 m.

d. It reach half its maximum height when time is 6.59 s or 38.41 s.

e. The rock is aloft for 45 seconds.

Step-by-step explanation:

Velocity is defined as the rate of change of position or the rate of displacement. $v(t)=\frac{ds}{dt}$
Acceleration is defined as the rate of change of velocity. $a(t)=\frac{dv}{dt}$

The rock's velocity is the derivative of the height function $s(t) = 36t - 0.8 t^2$

$v(t)=\frac{d}{dt}(36t - 0.8 t^2) \\\\\mathrm{Apply\:the\:Sum/Difference\:Rule}:\quad \left(f\pm g\right)'=f\:'\pm g'\\\\v(t)=\frac{d}{dt}\left(36t\right)-\frac{d}{dt}\left(0.8t^2\right)\\\\v(t)=36-1.6t$

The rock's acceleration is the derivative of the velocity function $v(t)=36-1.6t$

$a(t)=\frac{d}{dt}(36-1.6t)\\\\a(t)=-1.6$

b. The rock will reach its highest point when the velocity becomes zero.

$v(t)=36-1.6t=0\\36\cdot \:10-1.6t\cdot \:10=0\cdot \:10\\360-16t=0\\360-16t-360=0-360\\-16t=-360\\t=\frac{45}{2}=22.5$

It takes 22.5 seconds to reach the highest point.

c. The rock reach its highest point when t = 22.5 s

Thus

$s(22.5) = 36(22.5) - 0.8 (22.5)^2\\s(22.5) =405$

So the rock goes up to 405 m.

d. The maximum height is 405 m. So the half of its maximum height = $\frac{405}{2} =202.5 \:m$

To find the time it reach half its maximum height, we need to solve

$36t - 0.8 t^2=202.5\\36t\cdot \:10-0.8t^2\cdot \:10=202.5\cdot \:10\\360t-8t^2=2025\\360t-8t^2-2025=2025-2025\\-8t^2+360t-2025=0$

For a quadratic equation of the form $ax^2+bx+c=0$ the solutions are

$x_{1,\:2}=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$

$\mathrm{For\:}\quad a=-8,\:b=360,\:c=-2025:\\\\t=\frac{-360+\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2-\sqrt{2}\right)}{4}\approx 6.59\\\\t=\frac{-360-\sqrt{360^2-4\left(-8\right)\left(-2025\right)}}{2\left(-8\right)}=\frac{45\left(2+\sqrt{2}\right)}{4}\approx 38.41$

It reach half its maximum height when time is 6.59 s or 38.41 s.

e. It is aloft until s(t) = 0 again

$36t - 0.8 t^2=0\\\\\mathrm{Factor\:}36t-0.8t^2\rightarrow -t\left(0.8t-36\right)\\\\\mathrm{The\:solutions\:to\:the\:quadratic\:equation\:are:}\\\\t=0,\:t=45$

The rock is aloft for 45 seconds.

5 0

4 years ago

Someone help asapppp

Oxana [17]

Answer:

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

The sum of five consecutive numbers is -75. Which number is the least of these five numbers?

Ivan

Hello! I can help you with this! Do -75/5 to get -15. -15 will be your middle number. So for consecutive integers, -13 + -14 + -15 + -16 + -17 = 75. Those are five consecutive integers that have a sum of 75. The lowest of 5 integers is -17, because it’s the smallest of them all and the furthest to the left of the number line. A line further to the left of the number line means it’s smaller. Therefore, the rest of the five integers is -17.

6 0

3 years ago

Read 2 more answers

The height, h, in feet of a piece of cloth tied to a waterwheel in relation to sea level as a function of time, t, in seconds ca

Anni [7]

Considering the period of the cosine function, it is found that it takes 40 seconds for the wheel to complete one turn.

<h3>What is the period of the cosine function?</h3>

The cosine function is defined by:

f(x) = acos(bx + c) + d.

For the period, we have to look at coefficient b, and the period is:

P = 2π/|B|

For this problem, the function is given by:

h(x) = 15 cos(π/20)

Hence B = π/20, and the period is:

P = 2π/|B| = 2π/(π/20) = 2 x 20 = 40 seconds.

Hence it takes 40 seconds for the wheel to complete one turn.

More can be learned about the period of trigonometric functions at brainly.com/question/12502943

#SPJ1

7 0

2 years ago

Your friend claims that because each midsegment is half as long as the corresponding side of the triangle, the perimeter of the

AlexFokin [52]

Answer:
The claim is correct

Explanation:
Assume the given triangle ABC
perimeter of triangle ABC = AB + BC + CA ............> I

Now, we have:
D is the midpoint of AB, this means that:
AD = DB = (1/2) AB ..........> 1
E is the midpoint of AC, this means that:
AE = EC = (1/2) AC ...........> 2
DE is the midsegment in triangle ABC, this means that:
DE = (1/2) BC ...........> 3
perimeter of triangle ADE = AD + DE + EA
Substitute in this equation with the corresponding lengths in 1,2 and 3:
perimeter of triangle ADE = (1/2) AB + (1/2) BC = (1/2) AC
perimeter of triangle ADE = (1/2)(AB+BC+AC) .........> II

From I and II, we can prove that:
perimeter of triangle ADE = (1/2) perimeter of triangle ABC
Which means that:
perimeter of midsegment triangle is half the perimeter of the original triangle.

Hope this helps :)

7 0

3 years ago