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scoray [572]
3 years ago
13

Someone pls help me with 7 and 8, thank you so much!!

Mathematics
1 answer:
Sergio [31]3 years ago
4 0
7. A. -18 cm, because it changes -3 cm/per year, so multiply 6 years by -3 cm to get -18 cm

8. D. $20, because it rose +$2 over 10 days, you multiply 10 days by $2 to get $20 total
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`If I measure from the very top point of one wave to the same top point on the next wave, what have I measured?
morpeh [17]
I believe it’s wavelength!
7 0
2 years ago
x = c1 cos(t) + c2 sin(t) is a two-parameter family of solutions of the second-order DE x'' + x = 0. Find a solution of the seco
igomit [66]

Answer:

x=-cos(t)+2sin(t)

Step-by-step explanation:

The problem is very simple, since they give us the solution from the start. However I will show you how they came to that solution:

A differential equation of the form:

a_n y^n +a_n_-_1y^{n-1}+...+a_1y'+a_oy=0

Will have a characteristic equation of the form:

a_n r^n +a_n_-_1r^{n-1}+...+a_1r+a_o=0

Where solutions r_1,r_2...,r_n are the roots from which the general solution can be found.

For real roots the solution is given by:

y(t)=c_1e^{r_1t} +c_2e^{r_2t}

For real repeated roots the solution is given by:

y(t)=c_1e^{rt} +c_2te^{rt}

For complex roots the solution is given by:

y(t)=c_1e^{\lambda t} cos(\mu t)+c_2e^{\lambda t} sin(\mu t)

Where:

r_1_,_2=\lambda \pm \mu i

Let's find the solution for x''+x=0 using the previous information:

The characteristic equation is:

r^{2} +1=0

So, the roots are given by:

r_1_,_2=0\pm \sqrt{-1} =\pm i

Therefore, the solution is:

x(t)=c_1cos(t)+c_2sin(t)

As you can see, is the same solution provided by the problem.

Moving on, let's find the derivative of x(t) in order to find the constants c_1 and c_2:

x'(t)=-c_1sin(t)+c_2cos(t)

Evaluating the initial conditions:

x(0)=-1\\\\-1=c_1cos(0)+c_2sin(0)\\\\-1=c_1

And

x'(0)=2\\\\2=-c_1sin(0)+c_2cos(0)\\\\2=c_2

Now we have found the value of the constants, the solution of the second-order IVP is:

x=-cos(t)+2sin(t)

3 0
3 years ago
Evaluate the following expressions given the values below.
abruzzese [7]

Answer:

31

Step-by-step explanation:

ab + bc + ac for a = 2, b = 5, and c = 3

(2×5)+(5×3)+(2×3)

10+15+6

31

4 0
2 years ago
How many terms are in the arithmetic sequence 1313, 1616, 1919, ……, 7070, 7373?
Nataliya [291]
To find the number of terms in the arithmetic sequence, we need to use the formula 
a_{n}= a_{1}+(n-1)d    
where a_{n} is the nth number, a_{1} is the first number, n is the number of terms and d is the difference of the two consecutive numbers.
7373 = 1313 + (n - 1)(303)
7373 = 1313 + 303n - 303
7373 = 1010 + 303n
7373 - 1010 = 303n
6363 = 303n
6363 ÷ 303 = n
n = 21

Therefore, there are 21 terms in the arithmetic sequence given.
7 0
3 years ago
Can someone solve 5(x-4) – 6(x+2) < 4 the inequality plz i need help.
zhuklara [117]

Answer:

1) x=-36  

2) x>-11/12

3) x>-22

Step-by-step explanation:

6 0
3 years ago
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