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amid [387]
3 years ago
7

Find an equation of variation where y varies directly as x and y = 0.8 when x = 0.4

Mathematics
1 answer:
GrogVix [38]3 years ago
7 0

Answer:

y = 2x

Step-by-step explanation:

Given that y varies directly as x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = 0.8 when x = 0.4

k = \frac{y}{x} = \frac{0.8}{0.4} = 2

y = 2x ← equation of variation

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Can you help me i don’t know the answers
Advocard [28]
1)

An irrational number is a number that a) can't be written as a fraction of two whole numbers AND b) is an infinite decimal without any sort of pattern.

For the first answer choice, clearly \frac{1}{3} does not pass the first criterion so we look at the second choice.

Let's come back to \sqrt{2} and \pi.

\frac{2}{9} doesn't meet our first criterion, and let's skip \sqrt{3} for now.

It is often easier to disprove an irrational number than to prove one. There are a few famous irrationals to know (although there is an infinite number of irrationals). The most common are \sqrt{2},  \pi, e,  \sqrt{3}. For now, it's just helpful to know these and recognize them.

So we can check off \sqrt{2},  \pi and \sqrt{3}.

2) 

For this next question, we know that \sqrt{64} = 8. Clearly this isn't irrational. Likewise, \frac{1}{2} isn't irrational. \frac{16}{4} =  \frac{4}{4} = 1, which is rational, leaving only \frac{ \sqrt{20}}{5} =  \frac{2 \sqrt{5} }{5}. By process of elimination, this is the correct answer. Indeed, \sqrt{5} is an irrational number.

3) This notation means that we have 0.3636363636... and so on, to an infinite number of digits. It is called a repeating decimal.

But it can be written as a fraction because its pattern repeats, unlike for an irrational number.

Let's say x=0.36363636.... Would you agree that 100x=36.36363636...? (We choose to multiply by 100 because there are two decimals that repeat. For 1, choose 10, for 3 choose 1,000, and so on.)

Now, let's subtract x from 100x and solve.

100x=36.36363636\\-x \ \ \ \ \ \ \ -0.36363636\\99x=36\\\\x= \dfrac{36}{99}= \dfrac{4}{11}

Voila!
4 0
3 years ago
Read 2 more answers
How does a digit in the 10 thousand place compared toa digit in the 10 place
choli [55]
For example, in the number 14,509, fourteen thousand five hundred and nine, 1 is in the ten thousands place, and zero is in the tens place. 

                     1 4, 5 0 9
ten thousand^   ten^
6 0
3 years ago
Equivalent factored form for 10x^2+15x-9=2x^2+x-14
yanalaym [24]
Factored form - x= -1/2, -5/4
3 0
3 years ago
A Chevy Malibu has a fuel capacity of 18.5 gallons. This vehicle averages 666 miles per tank. Assume the relationship between fu
Nuetrik [128]

Answer:

180 miles

Step-by-step explanation:

Step one:

capacity of tank= 18.5gallons

vehicle averages 666 miles per tank.

Hence, the vehicle can travel 666 miles on 18.5 gallons

Required

The distance covered on 5 gallons

Step two:

vehicle can travel 666 miles on 18.5 gallons

the vehicle will go x miles on 5 gallons

cross multiply we have

5*666= 18.5*x

3330=18.5x

divide both sides by 18.5

x= 3330/18.5

x=180 miles

5 0
3 years ago
Two trains leave stations 360 miles apart at the same time and travel toward each other. One train travels at 70 miles per hour
cricket20 [7]
S=d/t     ⇒d=s*t
s=speed
d=distance
t=time

The first train :
d=x

x=70 miles/h*t                             ⇒   x=70t  (1)

The second train
d=360 miles - x

360 miles - x=80 miles/h*t          ⇒360-x=80t   ⇒ x=360-80t   (2)

therefore, with the equations (1) and (2) we have a systeme of equations:

x=70t
x=360-80t

we can solve this system of equations by equalization method.

70t=360-80t
70t+80t=360
150t=360
t=360/150=2.4     (≈2 hour  24 minutes)

Answer:  the first train meet with the second train in 2 hour 24 minutes. 


3 0
3 years ago
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