solve the following for x.

1)e^x^2-x=e^2

x^2-x = 2

I am not sure what to do now

2) e^-5x * e^4 = e

-5x + 4 = 1

x= 3/5

3) Suppose that the price p (in dollars) and the demand in x(thousands) of a commodity satisfy the demand equation 6p + x + xp =94. How fast is the demand changing at times when x= 4 and p=9 and the price is rising at the rate of $2 per week.

Would I take the derivative and then plug in 4 and 9?

4) solve: ln x = 4.5

e^lnx = e^4.5

x=e^4.5
5) evaluate: integral of x ln 4x dx

1/2 x^2 + 8x^2

6) evaluate the integral from 3 to 1 of x^3 - 3x +1

1/4x^4 + 1/6x^3 then plug in 3 and solve and the same for 1 and subtract

7) A bacteria culture grows exponentially according to the equation p(t)=1000e^.1t

a) what is the original amount of bacteria and what is the growth constant

the amount is 1000 and the constant is .1

b) what is the differential equation satisfied by p(t)

this one I am not sure about

c) what is the population after 5 days.

Just plug in 5 to the equation.

User Icon for Damon Damon answered
13 years ago

1)e^x^2-x=e^2

I bet you mean
1)e^(x^2-x)=e^2
x^2-x = 2
x^2 - x -2 = 0
(x-2)(x+1) = 0
x = 2 or -1

User Icon for Hannah Hannah answered
13 years ago

Are the rest that I did do correct?

User Icon for Damon Damon answered
13 years ago

3) Suppose that the price p (in dollars) and the demand in x(thousands) of a commodity satisfy the demand equation 6p + x + xp =94. How fast is the demand changing at times when x= 4 and p=9 and the price is rising at the rate of $2 per week.

Would I take the derivative and then plug in 4 and 9?
----------------------------------------
6 dp/dt + dx/dt +x dp/dt+ p dx/dt = 0
plug
6*2 + dx/dt + 4*2 + 9 dx/dt = 0
20 + 10 dx/dt = 0
dx/dt = -2

User Icon for Hannah Hannah answered
13 years ago

Is number 3 considered a related rates problem?

User Icon for Damon Damon answered
13 years ago

5) evaluate: integral of x ln 4x dx

= (x^2/2) ln 4x -x^2/4

User Icon for Hannah Hannah answered
13 years ago

1)evaluate: integral of x ln 4x dx

1/2 x^2 + 2x^2 Is this correct?

6) evaluate the integral from 3 to 1 of x^3 - 3x +1

1/4x^4 + 3/2 x^2 Is this the correct antiderivative?

User Icon for Damon Damon answered
13 years ago

6) evaluate the integral from 3 to 1 of x^3 - 3x +1

x^4/4
- 3 x^2 /2
+ x

User Icon for Hannah Hannah answered
13 years ago

thank you

User Icon for Damon Damon answered
13 years ago

Is number 3 considered a related rates problem?

I suppose so.
I should have been more careful about chain rule to show you what I did.
6p + x + xp =94.

6 dp/dx + dx/dx + x dp/dx + p dx/dx = 0

times dx/dt
6 dp/dx*dx/dt + dx/dx*dx/dt + x dp/dx*dx/dt + p dx/dx*dx/dt = 0

6 dp/dt +dx/dt +x dp/dt + p dx/dt = 0

User Icon for Damon Damon answered
13 years ago

7) A bacteria culture grows exponentially according to the equation p(t)=1000e^.1t

a) what is the original amount of bacteria and what is the growth constant
----------> 1000 because e^0 = 1, k = .1

the amount is 1000 and the constant is .1
------------> right

b) what is the differential equation satisfied by p(t)

this one I am not sure about
----------> dp/dt = .1 p
then of course
dp/p = .1 dt
ln p = .1 t + C
e^lnp = p = e^(.1t + C)
p = e^C e^(.1t) = c e^(.1t)

c) what is the population after 5 days.

Just plug in 5 to the equation.
--------> right