Select all the equations where x = 3 is a solution.

Problem PageQuestion The mass of a radioactive substance follows a continuous exponential decay model, with a decay rate paramet

asambeis [7]

Answer:

t = 1.51

Step-by-step explanation:

Exponential Model

The exponential model is often used to simulate the behavior of a magnitude that either grow or decay in proportion to the existing amount of that magnitude.

The model can be expressed as

$M=M_oe^{kt}$

In this case, Mo is the initial mass of the radioactive substance and k is a constant which value is positive if the mass is growing or negative if the mass is decaying.

The value of k is not precisely given in the question, we are assuming $k=-0.2$

The model is now

$M=M_oe^{-0.2t}$

We are required to compute the time it takes the mass to reach one-half of its initial value:

$\displaystyle \frac{M_o}{2}=M_oe^{-0.2t}$

Simplifying

$\displaystyle \frac{1}{2}=e^{-0.2t}$

Taking logarithms

$\displaystyle ln\frac{1}{2}=ln(e^{-0.2t})=-0.2t$

Solving for t

$\displaystyle t=-\frac{ln\frac{1}{2}}{0.2}=1.51$

6 0

3 years ago

Which number has a repeating decimal form?

blondinia [14]

Answer:

D. $\frac{2}{6}$

Step-by-step explanation:

2÷ 6 = 0.33333

As you can see 3 is repeating.

Therefore $\frac{2}{6}$ as repeating decimal form.

3 0

2 years ago

Find the equation of all tangent lines having slope of -1 that are tangent to the curve y=(9)/(x+1)

fredd [130]

Answer:

$f(x)=\frac9{x+1}\\ f'(x)=-\frac9{(x+1)^2}\\ f'(x)=-1\ \iff\ -\frac9{(x+1)^2}=-1\ \to \ \frac9{(x+1)^2}=1\ \to \ (x+1)^2=9\\ |x+1|=3\ \to \ x+1=3\ \vee\ x+1=-3\\ x_1=2\ \vee\ x_2=-4\\ f(x_1)=f(2)=\frac9{2+1}=3\\ f(x_2)=f(-4)=\frac9{-4+1}=-3$

First tangent line:

$y=f'(x_1)\cdot (x-x_1)+f(x_1)\ \to \ y=-1(x-2)+3\ \to \ y=-x+5$

Second tangent line:

$y=f'(x_2)\cdot (x-x_2)+f(x_2)\ \to \ y=-1(x+4)-3\ \to \ y=-x-7$

Notice: slope of -1 means that both $f'(x_1), \ f'(x_2)$ are equal to -1, so $f'(x_1)=-1 \ and \ f'(x_2)=-1$

6 0

2 years ago

Read 2 more answers

Which expression is equivalent to -4/7 - 8/9 + 4/7 - 9/8

olya-2409 [2.1K]

Answer:

I misunderstood the question before, but here are two expressions equivalent to -4/7 - 8/9 + 4/7 - 9/8.

71/72 + 70/72 +4/72

-1/7 - 3/7 - 5/9 - 3/9 + 2/7 +2/7 - 4/8 - 5/8

Solved: -2 1/72

Step-by-step explanation:

I could simply take the answer you get when combining all of the fractions, and I can make a new expression out of it. For example, I could use: 71/72+ 70/72+4/72. Or I could break apart all of the original fractions into smaller fractions. Example: -1/7 - 3/7 - 5/9 - 3/9 + 2/7 +2/7 - 4/8 - 5/8.

To solve: Start by combining -4/7 and 4/7 to make 0, shortening your equation. Then continue by making the fractions remaining, 8/9 and -9/8, have a common denominator. To do this, we multiply -8/9 by 8, and -9/8 by 9. Then, we have -64/72 and -81/72. Then, we can combine the numerators of the fractions, as they have common denominators, and we get the fraction -145/72. We can then simplify this to -2 1/72.

Hope this helps!

5 0

2 years ago

Hey! i’ll give brainliest please help.

Naya [18.7K]

Answer:

shah

:) hope this helps!

5 0

2 years ago