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asambeis [7]
2 years ago
5

HELP ASAP!!! x3+y3+z3

Mathematics
1 answer:
Paladinen [302]2 years ago
7 0

Answer:

= k

Step-by-step explanation:

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Find the unit tangent vector T and the principal unit normal vector N for the following parameterized curve.
const2013 [10]

Answer:

a.

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

b.

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)|}

a.

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

b.

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)

6 0
3 years ago
Let C(n, k) = the number of k-membered subsets of an n-membered set. Find (a) C(6, k) for k = 0,1,2,...,6 (b) C(7, k) for k = 0,
vladimir1956 [14]

Answer:

(a) C(6,0) = 1, C(6,1) = 6, C(6,2) = 15, C(6,3) = 20, C(6,4) = 15, C(6,5) = 6, C(6,6) = 1.

(b) C(7,0) = 1, C(7,1) = 7, C(7,2) = 21, C(7,3) = 35, C(7,4) = 35, C(7,5) = 21, C(7,6) = 7, C(7,7)=1.

Step-by-step explanation:

In this exercise we only need to recall the formula for C(n,k):

C(n,k) = \frac{n!}{k!(n-k)!}

where the symbol n! is the factorial and means

n! = 1\cdot 2\cdot 3\cdot 4\cdtos (n-1)\cdot n.

By convention 0!=1. The most important property of the factorial is n!=(n-1)!\cdot n, for example 3!=1*2*3=6.

(a) The explanations to the solutions is just the calculations.

  • C(6,0) = \frac{6!}{0!(6-0)!} = \frac{6!}{6!} = 1
  • C(6,1) = \frac{6!}{1!(6-1)!} = \frac{6!}{5!} = \frac{5!\cdot 6}{5!} = 6
  • C(6,2) = \frac{6!}{2!(6-2)!} = \frac{6!}{2\cdot 4!} = \frac{5!\cdot 6}{2\cdot 4!} = \frac{4!\cdot 5\cdot 6}{2\cdot 4!} = \frac{5\cdot 6}{2} = 15
  • C(6,3) = \frac{6!}{3!(6-3)!} = \frac{6!}{3!\cdot 3!} = \frac{5!\cdot 6}{6\cdot 6} = \frac{5!}{6} = \frac{120}{6} = 20
  • C(6,4) = \frac{6!}{4!(6-4)!} = \frac{6!}{4!\cdot 2!} = frac{5!\cdot 6}{2\cdot 4!} = \frac{4!\cdot 5\cdot 6}{2\cdot 4!} = \frac{5\cdot 6}{2} = 15
  • C(6,5) = \frac{6!}{5!(6-5)!} = \frac{6!}{5!} = \frac{5!\cdot 6}{5!} = 6
  • C(6,6) = \frac{6!}{6!(6-6)!} = \frac{6!}{6!} = 1.

(b) The explanations to the solutions is just the calculations.

  • C(7,0) = \frac{7!}{0!(7-0)!} = \frac{7!}{7!} = 1
  • C(7,1) = \frac{7!}{1!(7-1)!} = \frac{7!}{6!} = \frac{6!\cdot 7}{6!} = 7
  • C(7,2) = \frac{7!}{2!(7-2)!} = \frac{7!}{2\cdot 5!} = \frac{6!\cdot 7}{2\cdot 5!} = \frac{5!\cdot 6\cdot 7}{2\cdot 5!} = \frac{6\cdot 7}{2} = 21
  • C(7,3) = \frac{7!}{3!(7-3)!} = \frac{7!}{3!\cdot 4!} = \frac{6!\cdot 7}{6\cdot 4!} = \frac{5!\cdot 6\cdot 7}{6\cdot 4!} = \frac{120\cdot 7}{24} = 35
  • C(7,4) = \frac{7!}{4!(7-4)!} = \frac{6!\cdot 7}{4!\cdot 3!} = frac{5!\cdot 6\cdot 7}{4!\cdot 6} = \frac{120\cdot 7}{24} = 35
  • C(7,5) = \frac{7!}{5!(7-2)!} = \frac{7!}{5!\cdot 2!} = 21
  • C(7,6) = \frac{7!}{6!(7-6)!} = \frac{7!}{6!} = \frac{6!\cdot 7}{6!} = 7
  • C(7,7) = \frac{7!}{7!(7-7)!} = \frac{7!}{7!} = 1

For all the calculations just recall that 4! =24 and 5!=120.

6 0
3 years ago
The temperature falls from 10°F to -15° F. What is the difference in these<br> temperatures?
nadya68 [22]

Answer:

the difference is 25

Step-by-step explanation:

to get from 10 to 0 is 10 units and from 0 to -15 is 15

10+15 = 25

8 0
3 years ago
Which is true?<br><br>3+2=4+1 <br><br>1+2=3+3<br><br>0+3=3+1​
julsineya [31]

3 + 2 = 4 + 1 is true

1 +2 = 3 + 3 and 0 + 3 = 3+1 is not true

7 0
3 years ago
Emma is eating a bowl of soup for dinner. She estimates the bowl holds 2 quarts of soup . Do you think Emma's estimate is reason
FinnZ [79.3K]

Emma's estimate is not reasonable because a serving of soup is typically about 1-2 cups and 2 quarts = 8 cups.

would you eat 8 cups of soup? no.
4 0
3 years ago
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