Question

check my work please will give medals if you tell if this is right or not!!!
Let f(x)=x+5 and g(x)=x^2. find (g o f) (4)
A. 9 <--- my answer
B. 81
C. 20
D. 1
2. police can estimate the speed of a vehicle before the brakes are applied using the formula 0.75d=s^2/30.25, where s is the speed in miles per hour and d is the length of the vehicle's skid marks. what was the approximate speed of a vehicle that left skid marks measuring 140 feet?
A. about 10 miles per hour <-- my answer
B. about 75 miles per hour
C. about 15 miles per hour
D. about 56 miles per hour

Answer 1

3. you can model the population of a certain city between 1955-2000 by the radial funciton P(x)=55000square root (x-1945). using this model, in which year was the population of that city 220,000?
A. 1949 <--- my answer
B. 1961
C. 1953
D. 1957

4.what is the inverse of f if f(x)=3^square root (x-4)
A. f^-1(x)=x^3+64
B. f^-1(x)=x^3+4 <--- my answer
C. f^-1(x)=4-^3 square root (x)
D. f^-1(x)=1/3^ square root (x-4)

Answer 2

Sorry, question A will be 81.

Answer 3

Second answer will be D.

Answer 4

Hey @Saeeddiscover do you like Paul Dirac?

Answer 5

Yes, why?

Answer 6

so does that mean i did 3 and 4 right ?

Answer 7

@rockstargirl17 is the last question \[f(x)=3^{\sqrt{x-4}}\]

Answer 8

3. 220000 = 55000square root (x-1945)
divide both sides by 55000
4 = sqrt(x-1945)
square
16 = x - 1945
x= 1961

Answer 9

Question D doesn't seem to be solved right. I am sorry ....

Answer 10

Oops! I meant question 4. could you tell me what is the option 3 in the question 4? it doesn't seem to be correct ....

Answer 11

Hey @rockstargirl17????

Answer 12

4.what is the inverse of f if f(x)=3^square root (x-4)
A. f^-1(x)=x^3+64
B. f^-1(x)=x^3+4 <--- my answer
C. f^-1(x)=4-^3 square root (x)
D. f^-1(x)=1/3^ square root (x-4)

Answer 13

@Saeeddiscover

Answer 14

Option C is somehow given incorrectly. In any case, other options would never be the answer. I think option C can be true here.

Answer 15

Look for question 4, if the function is an exponential then its inverse MUST be a logarithmic function! I don't see any logarithms in the options which suggests the answer is not among the options! @Saeeddiscover @rockstargirl17

Answer 16

You don't need to mix himself. If (a, b) is a point belonging to the function f, so (b, a) must be a point belonging to its inverse. Suppose (a, b) = (3, 5), Is there any function in the list to satisfy (5, 3)?

Answer 17

Do you think it is an exponential function? @Isaiah.Feynman

Answer 18

I don't think so. sorry ...

Answer 19

Then what is f(x)=3^square root (x-4)?? It can only be

Answer 20

\[f(x)=3^{\sqrt{x-4}}\]

Answer 21

It is a simple function.

Answer 22

A simple exponential function you mean? :D

Answer 23

No. exponential functions are not given in forms like this. an exponential function is defined as the inverse of a logarithmic function f and is written as y = exp(x)

Answer 24

Okay. That explains why I get a strange "inverse function" because I have being treating it as an exponential function.