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3 years ago

If the diameter of a sphere is doubled, its surface becomes

1 answer:

8 0

Volumes scale as the cube of a corresponding dimension. Therefore, if the radius of a sphere is doubled (r becomes 2r), the surface area becomes 2 squared, or 4 times the original surface area. The volume would become 2 cubed, or 8 times the original volume.

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Find the general solution of x'1 = 3x1 - x2 + et, x'2 = x1.

Ann [662]

Note that if ${x_2}'=x_1$ , then ${x_2}''={x_1}'$ , and so we can collapse the system of ODEs into a linear ODE:

${x_2}''=3{x_2}'-x_2+e^t$
${x_2}''-3{x_2}'+x_2=e^t$

which is a pretty standard linear ODE with constant coefficients. We have characteristic equation

$r^2-3r+1=\left(r-\dfrac{3+\sqrt5}2\right)\left(r+\dfrac{3+\sqrt5}2\right)=0$

so that the characteristic solution is

${x_2}_C=C_1e^{(3+\sqrt5)/2\,t}+C_2e^{-(3+\sqrt5)/2\,t}$

Now let's suppose the particular solution is ${x_2}_p=ae^t$ . Then

${x_2}_p={{x_2}_p}'={{x_2}_p}''=ae^t$

and so

$ae^t-3ae^t+ae^t=-ae^t=e^t\implies a=-1$

Thus the general solution for $x_2$ is

$x_2=C_1e^{(3+\sqrt5)/2\,t}+C_2e^{-(3+\sqrt5)/2\,t}-e^t$

and you can find the solution $x_1$ by simply differentiating $x_2$ .

7 0

3 years ago

How do i solve this step by step? <br><br> 3( q – 3 ) = 6

mote1985 [20]

Answer:

3q-9=6

3q=9+6

3q=15

q=5

7 0

2 years ago

Which ordered pairs in the form (x, y)(x, y) are solutions to the equation

Scilla [17]

4x - 5y = 24

4(6) - 5(0) = 24
24 - 0 = 24
24 = 24 (correct)....so (6,0) is a solution

4(1) - 5(-4) = 24
4 + 20 = 24
24 = 24 (correct)...and (1,-4) is a solution

3 0

2 years ago

Read 2 more answers

3x^2(x^3-1)+2x^3(2x^2+2) <br> Whats the simplified answer?

ahrayia [7]

Answer:

$\large\boxed{7x^5+4x^3-3x^2}$

Step-by-step explanation:

$3x^2(x^3-1)+2x^3(2x^2+2)\qquad\text{use the distributive property:}\ a(b+c)=ab+ac\\\\=(3x^2)(x^3)+(3x^2)(-1)+(2x^3)(2x^2)+(2x^3)(2)\qquad\text{use}\ a^na^m=a^{n+m}\\\\=3x^{2+3}-3x^2+4x^{3+2}+4x^3\\\\=3x^5-3x^2+4x^5+4x^3\qquad\text{combine like terms}\\\\=(3x^5+4x^5)-3x^2+4x^3\\\\=7x^5+4x^3-3x^2$

4 0

2 years ago

BartSMP [9]

Answer:

Step-by-step explanation:

Causation is often confused with correlation because they are so similar. B would mean that pollution is caused from something (lets say greenhouse gases for example) which then results in more cases of heart disease.

Causation is when the first variable may bring the second into existence or may cause the incidence of the second variable to fluctuate. So, causation is the capacity of one variable to influence another. Which, would make B, a suitable candidate.

8 0

2 years ago