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2 years ago

Please help I dont understand

Mathematics

1 answer:

crimeas [40]2 years ago

8 0

Answer:

A number and maybe some letters

Step-by-step explanation:

It is a number and maybe some letters

I hope this helps! :)

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If y=1/2x+4, then find the equation of the line parallel through the point (6,3).

tatyana61 [14]

Answer:

x=2y

Step-by-step explanation:

random guess

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2 years ago

Part A: Find a rational number that is between 7.7 and 7.9. Explain why it is rational. (2 points)

8_murik_8 [283]

A rational number is any number that can be written as the ratio between two other numbers i.e. in the form $\frac{a}{b}$

Part A:
An easy choice that makes sense is 7.8, right in the middle. To prove that it's rational we need to write it as a ratio. In this case we have $7.8=\frac{78}{10}$

Part B:
We need a number that can't be written as a ratio (because it neither terminates nor repeats). Some common ones are $\sqrt{2}$ , $e$ , $\phi$ and $\pi$ so it makes sense to try and use those to build our number. In this case $\frac{11\sqrt{2}}{5}\approx7.78$ works nicely.

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3 years ago

Find the unit tangent vector T and the principal unit normal vector N for the following parameterized curve.

const2013 [10]

Answer:

$T(t) = ( -sin(t^2), cos(t^2) )\\\\N(t) = T'(t) / |T'(t) | = (-cos(t^2) , -sin(t^2))$

$T(t) =r'(t)/|r'(t)| = (2t/ \sqrt{4t^2 + 36} , -6/\sqrt{4t^2 + 36},0)$

$N(t) =T(t)/|T'(t)| = (3/(9 + t^2)^{1/2} , t/(9 + t^2)^{1/2},0)$

Step-by-step explanation:

Remember that for any curve $r(t)$

The tangent vector is given by

$T(t) = \frac{r'(t) }{| r'(t)| }$

And the normal vector is given by

$N(t) = \frac{T'(t)}{|T'(t)|}$

For this case, using the chain rule

$r'(t) = ( -10*2tsin(t^2) , 102t cos(t^2) )\\$

And also remember that

$|r'(t)| = \sqrt{(-10*2tsin(t^2))^2 + ( 10*2t cos(t^2) )^2} \\\\ = \sqrt{400 t^2*( sin(t^2)^2 + cos(t^2) ^2 })\\=\sqrt{400t^2} = 20t$

Therefore

$T(t) = r'(t) / |r'(t) | = ( -10*2tsin(t^2) , 10*2t cos(t^2) )/ 20t\\\\ = ( -10*2tsin(t^2)/ 20t , 10*2t cos(t^2) / 20t )\\= ( -sin(t^2), cos(t^2) )$

Similarly, using the quotient rule and the chain rule

$T'(t) = ( -2t cos(t^2) , -2t sin(t^2))$

And also

$|T'(t)| = \sqrt{ ( -2t cos(t^2))^2 + (-2t sin(t^2))^2} = \sqrt{ 4t^2 ( ( cos(t^2))^2 + ( sin(t^2))^2)} = \sqrt{4t^2} \\ = 2t$

Therefore

$N(t) = T'(t) / |T'(t) | = (-cos(t^2) , -sin(t^2))$

Notice that

1. $|N(t)| = |T(t) | = \sqrt{ cos(t^2)^2 + sin(t^2)^2 } = \sqrt{1} = 1$

2. $N(t)*T(T) = cos(t^2) sin(t^2 ) - cos(t^2) sin(t^2 ) = 0$

Simlarly

$r'(t) = (2t,-6,0) \\$

and

$|r'(t)| = \sqrt{(2t)^2 + 6^2} = \sqrt{4t^2 + 36}$

Therefore

$T(t) =r'(t)/|r'(t)| = (2t/ \sqrt{4t^2 + 36} , -6/\sqrt{4t^2 + 36},0)$

Then

$T'(t) = (9/(9 + t^2)^{3/2} , (3 t)/(9 + t^2)^{3/2},0)$

and also

$|T'(t)| = \sqrt{ ( (9/(9 + t^2)^{3/2} )^2 + ( (3 t)/(9 + t^2)^{3/2})^2 + 0^2 }\\= 3/(t^2 + 9 )$

And since

$N(t) =T(t)/|T'(t)| = (3/(9 + t^2)^{1/2} , t/(9 + t^2)^{1/2},0)$

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2 years ago

There are 9 marbles in a bag, 3 of those marbles are red. what is the probability of picking a red marble randomly from the bag?

boyakko [2]

Answer:

1/3 because there's more of the other marbles than red

Step-by-step explanation:

7 0

2 years ago

What is 6(5-8v)+12=-54

stira [4]

V=2 bc when u distribute the 6 to the numbers in the parenthesis u get 30-48v+12=54 then u subract 12 on both sides getting 30-48v=-66 then u subtract 30 on both sides making it -48v=-96 and mental math leads to -48•2=-96

4 0

3 years ago

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