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3 years ago

What is the domain of the function f(x)= ln(x^2-4)? Please show your work.

Mathematics

2 answers:

Orlov [11]3 years ago

8 0

Hello,

A ln must have like argument a positive number.

x²-4>0 whose roots are 2 and -2.
To be positive, the value of must be exterior of the roots

so -infinity<x<-2 or 2<x<infinity

Dom f(x)=IR - [-2; 2].

snow_lady [41]3 years ago

6 0

F(x) = ㏑(x² - 4)

Domain: {-2 ≤ x ≤ 2}, or [-2, 2]

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Multiple choice please please answer

lakkis [162]

Answer:

$\purple { \boxed{x = 25 \times \sin \: 39 \degree}}$

Step-by-step explanation:

$\sin \: 39 \degree = \frac{x}{25} \\ 25 \times \sin \: 39 \degree = x \\ \huge \red{ \boxed{x = 25 \times \sin \: 39 \degree}}$

4 0

3 years ago

Thank you so much, my friend

ss7ja [257]

Answer:

Step-by-step explanation:

This is quite a doozy, my friend. We will set up a d = rt table, fill it in...and pray.

The table will look like this before we even fill anything in:

d = r * t

SUV

sedan

Ok now we start to pick apart the problem. Motion problems are the hardest of all story problems ever. This is because there are about 100 ways a motion problem can be presented. So far what we KNOW for an indisputable fact is that the distance from Georgetown to Greenville is 120 km. So we fill that in, making the table:

d = r * t

SUV 120

sedan 120

The next part is derived from the sentence "After an hour, the SUV was 24 km ahead of the sedan." This tells us the rate of the SUV in terms of the sedan. If the SUV is 24 km ahead of the sedan in 1 hour, that tells us that the rate of the sedan is r and the rate of the SUV is r + 24 km/hr. BUT we have other times in this problem, one of them being 25 minutes. We have a problem here because the times either have to be in hours or minutes, but not both. So we will change that rate to km/min. Doing that:

24 $\frac{km}{hr}$ × $\frac{1hr}{60min}=.4\frac{km}{min}$ So now we can fill in the rates in the table:

d = r * t

SUV 120 = r + .4

sedan 120 = r

They left at the same time, so now the table looks like this:

d = r * t

SUV 120 = r + .4 * t

sedan 120 = r * t

We will put in the time difference of 25 minutes in just a sec.

If d = rt, then the equation for each row is as follows:

SUV: 120 = (r + .4)t

sedan: 120 = rt

Since the times are the same (because they left at the same time, we will set the equations each equal to t. The distances are the same, too, I know that, but if we set the distances equal to each other and then solve the equations for a variable, the distances cancel each other out, leaving us with nowhere to go. Trust me, I tried that first! Didn't work.

Solving the first equation for time:

sedan: $\frac{120}{r}=t$ That's the easy one. Now the SUV. This is where that time difference of 25 minutes comes in from the last sentence. Let's think about what that sentence means in terms of the times of each of these vehicles. If the sedan arrived 25 minutes after the SUV, then the sedan was driving 25 minutes longer; conversely, if the sedan arrived 25 minutes after the SUV, then the SUV was driving 25 minutes less than the sedan. The latter explanation is the one I used in the equation. Again, if the SUV was driving 25 minutes less than the sedan, and the equations are solved for time, then the equation for the SUV in terms of time is

$\frac{120}{r+.4}=t-25$ and we solve that for t:

$\frac{120}{r+.4}+25=t$

Again, going off the fact that times they both leave are the same, we set the equations equal to one another and solve for r:

$\frac{120}{r+.4}+25=\frac{120}{r}$

I began by first multiplying everything through by (r + .4) to get rid of it in the denominator. Doing that:

$[r+.4](\frac{120}{r+.4}) +[r+.4](25)=[r+.4](\frac{120}{r})$ which simplifies very nicely to

$120+25(r+.4)=\frac{120}{r}(r+.4)$ So maybe it's not so nice. Let's keep going:

$120+25r+10=\frac{120r}{r}+\frac{48}{r}$ and keep going some more:

$130+25r=120+\frac{48}{r}$ and now we multiply everything through by r to get rid of THAT denominator:

$r(130)+r(25r)=r(120)+r(\frac{48}{r})$ giving us:

$130r+25r^2=120r+48$ Now we have a second degree polynomial we have to solve by factoring. Get everything on one side and factor using the quadratic formula.

$25r^2+10r-48=0$

That factors to

r = 1.2 and r = -1.6 and both of those rates are in km/minute. First of all, we cannot have a negative rate (this is not physics where we are dealing with velocity which CAN be negative) so we throw out the -1.6 and convert the rate of 1.2 km/minute back to km/hr:

$1.2\frac{km}{min}$ × $\frac{60min}{1hr}$ and we get

r = 72 km/h, choice B.

Wow...what a pain THAT was, right?!

5 0

2 years ago

A 4-ft vertical post casts a 12-in shadow at the same time a nearby cell phone tower casts a 122-ft shadow. How tall is the c

zepelin [54]

Answer:

the cell phone tower is 488 ft

Step-by-step explanation:

change 12 in = 1ft

4ft x ft

------------------- = ----------------

1ft shadow 122 ft shadow

using cross products

4 * 122 = 1 * x

488 = x

3 0

3 years ago

The tortoise and the hare are in a road race to defend the honor of their breed. the tortoise crawls the entire 1000. m distance

jolli1 [7]

<span>The tortoise crawls the whole 1000 m at 0.2 m/s, therefore, you must divide the distance by the rate of travel to find the time it took to complete the race. This gives us a time of 5,000 seconds to crawl the thousand meters. The hare runs the first 200 meters at 2 m/s, meaning that takes 100 seconds. The last 800 meters divided by the speed of 3 m/s gives us a time of 266 seconds. These two numbers must be added to the hare's rest time, converted from 1.3 hours into seconds by multiplying that number by 60 (for minutes in an hour) then 60 again (for seconds in a minute). 1.3 hours is equal to 4680 seconds. Therefore, the whole race took the hare 5,046 seconds, making it slightly slower than the hare, who finished in 5,000 seconds flat.</span>

5 0

3 years ago

The equation that represents the canned goods order is 24x+64y=384

Lubov Fominskaja [6]

The x-intercept is (16, 0) and y- intercept is (0, 6).

<h3>What is intercept?</h3>

The x-intercept is the point where a line crosses the x-axis, and the y-intercept is the point where a line crosses the y-axis.

Given: 24x+64y=384

For y- intercept, put x=0

Then,

24*0+64y=384

64y= 384

y= 6

Now, for x- intercept put y=0

Then,

24x+64*0=384

24x= 384

x= 15

Hence, the x-intercept is (16, 0) and y- intercept is (0, 6).

Learn more about this concept here:

brainly.com/question/2334999

#SPJ1

5 0

2 years ago