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MA_775_DIABLO [31]
3 years ago
9

what is the common ratio of a geometric progression were the first term is 3 and the 4th term is 648​

Mathematics
1 answer:
zimovet [89]3 years ago
8 0

Answer:

r = 6

Step-by-step explanation:

Given

a = 3 --- First, term

T_4 = 648 --- Fourth term

Required: Determine the common ratio

The nth term of a GP is

T_n = ar^{n-1

Substitute 4 for n

T_4 = ar^{4-1

T_4 = ar^{3

Substitute 648 and 3 for T4 and 3 respectively.

648 = 3 * r^{3

r^3 = 216

Take cube roots of both sides

r =\sqrt[3]{216}

r = 6

<em>The common ratio is 6</em>

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If Hector is 8 years old and Mary is 3 years old how old will Mary be when Hector is 16
IRINA_888 [86]
Okay so 8 (hector) - 3(Mary) = 5 years apart
So, 16 (hector) - 5 (years apart) = 11 (Mary’s age)
7 0
3 years ago
The sum of two numbers is -17. Their difference is 41. Find the numbers
Alex787 [66]

Answer:

x = 12

y = -29

Step-by-step explanation:

Our given equations: x + y = -17 and x - y = 41

Solve for x and substitute.

x = -17 - y

(-17 - y) - y = 41

-17 - 2y = 41

2y = -58

y = -29

Solve for x using y

x + (-29) = -17

x = 12

3 0
2 years ago
Find the direction cosines and direction angles of the vector. (Give the direction angles correct to the nearest degree.) 5, 1,
Dahasolnce [82]

Answer:

The direction cosines are:

\frac{5}{\sqrt{42} }, \frac{1}{\sqrt{42} }  and  \frac{4}{\sqrt{42} }  with respect to the x, y and z axes respectively.

The direction angles are:

40°,  81° and  52° with respect to the x, y and z axes respectively.

Step-by-step explanation:

For a given vector a = ai + aj + ak, its direction cosines are the cosines of the angles which it makes with the x, y and z axes.

If a makes angles α, β, and γ (which are the direction angles) with the x, y and z axes respectively, then its direction cosines are: cos α, cos β and cos γ in the x, y and z axes respectively.

Where;

cos α = \frac{a . i}{|a| . |i|}               ---------------------(i)

cos β = \frac{a.j}{|a||j|}               ---------------------(ii)

cos γ = \frac{a.k}{|a|.|k|}             ----------------------(iii)

<em>And from these we can get the direction angles as follows;</em>

α =  cos⁻¹ ( \frac{a . i}{|a| . |i|} )

β = cos⁻¹ ( \frac{a.j}{|a||j|} )

γ = cos⁻¹ ( \frac{a.k}{|a|.|k|} )

Now to the question:

Let the given vector be

a = 5i + j + 4k

a . i =  (5i + j + 4k) . (i)

a . i = 5         [a.i <em>is just the x component of the vector</em>]

a . j = 1            [<em>the y component of the vector</em>]

a . k = 4          [<em>the z component of the vector</em>]

<em>Also</em>

|a|. |i| = |a|. |j| = |a|. |k| = |a|           [since |i| = |j| = |k| = 1]

|a| = \sqrt{5^2 + 1^2 + 4^2}

|a| = \sqrt{25 + 1 + 16}

|a| = \sqrt{42}

Now substitute these values into equations (i) - (iii) to get the direction cosines. i.e

cos α = \frac{5}{\sqrt{42} }

cos β =  \frac{1}{\sqrt{42} }              

cos γ =  \frac{4}{\sqrt{42} }

From the value, now find the direction angles as follows;

α =  cos⁻¹ ( \frac{a . i}{|a| . |i|} )

α =  cos⁻¹ ( \frac{5}{\sqrt{42} } )

α =  cos⁻¹ (\frac{5}{6.481} )

α =  cos⁻¹ (0.7715)

α = 39.51

α = 40°

β = cos⁻¹ ( \frac{a.j}{|a||j|} )

β = cos⁻¹ ( \frac{1}{\sqrt{42} } )

β = cos⁻¹ ( \frac{1}{6.481 } )

β = cos⁻¹ ( 0.1543 )

β = 81.12

β = 81°

γ = cos⁻¹ ( \frac{a.k}{|a|.|k|} )

γ = cos⁻¹ (\frac{4}{\sqrt{42} })

γ = cos⁻¹ (\frac{4}{6.481})

γ = cos⁻¹ (0.6172)

γ = 51.89

γ = 52°

<u>Conclusion:</u>

The direction cosines are:

\frac{5}{\sqrt{42} }, \frac{1}{\sqrt{42} }  and  \frac{4}{\sqrt{42} }  with respect to the x, y and z axes respectively.

The direction angles are:

40°,  81° and  52° with respect to the x, y and z axes respectively.

3 0
3 years ago
The price of a technology stock has dropped to $9.71 today. Yesterday's price was $9.80. Find the percentage decrease.
Vadim26 [7]

Answer:

The percentage decrease = 0.9%

Step-by-step explanation:

  • Initial value = $9.80
  • Final value = $9.71

Using the formula

Percentage Decrease = [ (Initial Value - Final Value) / |Initial Value| ] × 100

                                    = [(9.80 - 9.71 ) / (9.80)] × 100

                                    = [0.09 / 9.80] × 100

                                    = 0.009 × 100  

                                    = 0.9%

Therefore, the percentage decrease = 0.9%

4 0
3 years ago
A student lives 3 miles from the library . He is riding his bike to the library . The distance he has remaining y is a function
astraxan [27]

Would the answer be 6? or 9?

4 0
3 years ago
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