PLEASE HELP! GIVING 40 POINTS!

Find f(-1) if f(x) = -3x - 5 Choices A. -9 B. -8 C. -2 D. 2

GenaCL600 [577]

Answer:

Step-by-step explanation:

All you have to do is plug in -1 for x in the equation

f(-1)= -3(-1)-5

-3 times -1 = 3

Then you need to subtract 5 leaving it to be 3-5 = -2

Therefore the answer is C. - 2

5 0

4 years ago

Read 2 more answers

Sally Sue had spent all day preparing for the prom. All the glitz and the glamour of the evening fell apart as she stepped out o

Nuetrik [128]

We have the function

$p(t)=550(1-e^{-0.039t})$

Therefore we want to determine when we have

$p(t_0)=550$

It means that the term

$e^{-0.039t}$

Must go to zero, then let's forget the rest of the function for a sec and focus only on this term

$e^{-0.039t}\rightarrow0$

But for which value of t? When we have a decreasing exponential, it's interesting to input values that are multiples of the exponential coefficient, if we have 0.039 in the exponential, let's define that

$\alpha=\frac{1}{0.039}$

The inverse of the number, but why do that? look what happens when we do t = α

$e^{-0.039t}\Rightarrow e^{-0.039\alpha}\Rightarrow e^{-1}=\frac{1}{e}$

And when t = 2α

$e^{-0.039t}\Rightarrow e^{-0.039\cdot2\alpha}\Rightarrow e^{-2}=\frac{1}{e^2}$

We can write it in terms of e only.

And we can find for which value of α we have a small value that satisfies

$e^{-0.039t}\approx0$

Only using powers of e

Let's write some inverse powers of e:

$\begin{gathered} \frac{1}{e}=0.368 \\ \\ \frac{1}{e^2}=0.135 \\ \\ \frac{1}{e^3}=0.05 \\ \\ \frac{1}{e^4}=0.02 \\ \\ \frac{1}{e^5}=0.006 \end{gathered}$

See that at t = 5α we have a small value already, then if we input p(5α) we can get

$\begin{gathered} p(5\alpha)=550(1-e^{-0.039\cdot5\alpha}) \\ \\ p(5\alpha)=550(1-0.006) \\ \\ p(5\alpha)=550(1-0.006) \\ \\ p(5\alpha)=550\cdot0.994 \\ \\ p(5\alpha)\approx547 \end{gathered}$

That's already very close to 550, if we want a better approximation we can use t = 8α, which will result in 549.81, which is basically 550.

Therefore, we can use t = 5α and say that 3 people are not important for our case, and say that it's basically 550, or use t = 8α and get a very close value.

In both cases, the decimal answers would be

$\begin{gathered} 5\alpha=\frac{5}{0.039}=128.2\text{ minutes (good approx)} \\ \\ 8\alpha=\frac{8}{0.039}=205.13\text{ minutes (even better approx)} \end{gathered}$

7 0

2 years ago

Match the following items by evaluating the expression for x = -2.

solong [7]

Answer:

see below

Step-by-step explanation:

x^-2 = 1/x^2 Let x = -2 1/ (-2)^2 = 1/4

x^-1 = 1/x^1 Let x = -2 1/ (-2)^1 = 1/(-2) = -1/2

x^0 = 1

x^1 = x Let x = -2 (-2)

x^2 = Let x = -2 (-2)^2 = 4