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marissa [1.9K]
3 years ago
7

(b) For those values of k, verify that every member of the family of functions y = A sin(kt) + B cos(kt) is also a solution. y =

A sin(kt) + B cos(kt) ⇒ y' = Ak cos(kt) − Bk sin(kt) ⇒ y'' = −Ak2 sin(kt) − Bk2 cos(kt).

Mathematics
1 answer:
frutty [35]3 years ago
4 0

Answer:

Check attachment for complete question

Step-by-step explanation:

Given that,

y=Coskt

We are looking for value of k, that satisfies 4y''=-25y

Let find y' and y''

y=Coskt

y'=-kSinkt

y''=-k²Coskt

Then, applying this 4y'"=-25y

4(-k²Coskt)=-25Coskt

-4k²Coskt=-25Coskt

Divide through by Coskt and we assume Coskt is not equal to zero

-4k²=-25

k²=-25/-4

k²=25/4

Then, k=√(25/4)

k= ± 5/2

b. Let assume we want to use this

y=ASinkt+BCoskt

Since k= ± 5/2

y=A•Sin(±5/2t)+ B •Cos(±5/2t)

y'=±5/2ACos(±5/2t)-±5/2BSin(±5/2t)

y''=-25/4ASin(±5/2t)-25/4BCos(±5/2t

Then, inserting this to our equation given to check if it a solution to y=ASinkt+BCoskt

4y''=-25y

For 4y''

4(-25/4ASin(±5/2t)-25/4BCos(±5/2t))

-25A•Sin(±5/2t)-25B•Cos(±5/2t).

Then,

-25y

-25(A•Sin(±5/2t)+ B •Cos(±5/2t))

-25A•Sin(±5/2t) - 25B •Cos(±5/2t)

Then, we notice that, 4y'' is equal to -25y, then we can say that y=Coskt is a solution to y=ASinkt+BCoskt

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Answer:

The average rate of change of the function over the interval is of 6.

Step-by-step explanation:

Average rate of change:

The average rate of change of a function h(x) over an interval [a,b] is given by:

A = \frac{h(b)-h(a)}{b-a}

In this question:

Over the interval [-9,-2], so a = -9, b = -2, b - a = -2 -(-9) = 7

The function is:

h(x) = -x^2 - 5x + 14

h(-9) = -9^2 -5(-9) + 14 = -81 + 45 + 14 = -22

h(-2) = -2^2 -5(-2) + 14 = -4 + 10 + 14 = 20

Then

A = \frac{h(-2)-h(-9)}{7} = \frac{20-(-22)}{7} = \frac{42}{7} = 6

The average rate of change of the function over the interval is of 6.

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Step-by-step explanation:

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Whst will be the multiplicative inverse of<br>3/5 - 4/27 + 5/18​
Yuliya22 [10]

Answer:





Find the multiplicative inverse of the following

(i) -13    (ii) -13/19    (iii) 1/5    (iv) -5/8 × -3/7    (v) -1 × -2/5

(vi) -1

Solution:

The reciprocal of a given rational number is known as its multiplicative inverse. The product of a rational number and its multiplicative inverse is 1.

(i) The Multiplicative inverse of -13 is -1/13

∵ -13 × (-1/13) = 1

(ii) The Multiplicative inverse of -13/19 is -19/13

∵ -13/19 × (-19/13) = 1

(iii) The Multiplicative inverse of 1/5 is 5

∵ 1/5 × 5 = 1

(iv) The Multiplicative inverse of -5/8 × -3/7 is 56/15

∵ -5/8 × (-3/7) = 15/56 and 15/56 × 56/15 = 1

(v) The Multiplicative inverse of -1 × -2/5 is 5/2

∵ -1 × (-2/5) = 2/5 and 2/5 × 5/2 = 1

(vi) The Multiplicative inverse of -1 is -1

∵ -1 × (-1) = 1

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