All categories

2 years ago

If f(x)=3x²-5x+4, then f(-2) =

Mathematics

1 answer:

igomit [66]2 years ago

4 0

Answer:

Step-by-step explanation:

First let's re-write the equation:

f(x) = 3x² - 5x + 4

If f(-2). then we can re-write the equation as:

f(-2) = 3(-2)² - 5(-2) + 4

We must solve for exponent first: (-2)² = 4

f(-2) = 3(4) - 5(-2) + 4

Then solve for multiplication:

f(-2) = 12 + 10 + 4

Finally addition:

f(-2) = 26

that means that in a function, if X = -2, then F is equal to 26

You might be interested in

(EASY MULTIPLE CHOICE I BEG YOU)

iogann1982 [59]

1) its number 2. 30x^7y^4

8 0

2 years ago

I need help solving this please

Kruka [31]

I really hope this helps this is what my teacher said to do in the type of problem

7 0

3 years ago

In a random sample of 150 customers of a high-speed Internetprovider, 63 said that their service had been interrupted one ormore

erastovalidia [21]

Answer:

a) The 95% confidence interval would be given by (0.341;0.499)

b) The 99% confidence interval would be given by (0.316;0.524)

c) n=335

d)n=649

Step-by-step explanation:

1) Notation and definitions

$X_{IS}=63$ number of high speed internet users that had been interrupted one or more times in the past month.

$n=150$ random sample taken

$\hat p_{IS}=\frac{63}{150}=0.42$ estimated proportion of high speed internet users that had been interrupted one or more times in the past month.

$p_{IS}$ true population proportion of high speed internet users that had been interrupted one or more times in the past month.

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

1) Part a

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by:

$t_{\alpha/2}=-1.96, t_{1-\alpha/2}=1.96$

The confidence interval for the mean is given by the following formula:

$\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$

If we replace the values obtained we got:

$0.42 - 1.96\sqrt{\frac{0.42(1-0.42)}{150}}=0.341$

$0.42 + 1.96\sqrt{\frac{0.42(1-0.42)}{150}}=0.499$

The 95% confidence interval would be given by (0.341;0.499)

2) Part b

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by:

$t_{\alpha/2}=-2.58, t_{1-\alpha/2}=2.58$

The confidence interval for the mean is given by the following formula:

$\hat p \pm z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$

If we replace the values obtained we got:

$0.42 - 2.58\sqrt{\frac{0.42(1-0.42)}{150}}=0.316$

$0.42 + 2.58\sqrt{\frac{0.42(1-0.42)}{150}}=0.524$

The 99% confidence interval would be given by (0.316;0.524)

3) Part c

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.05$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.42(1-0.42)}{(\frac{0.05}{1.96})^2}=374.32$

And rounded up we have that n=335

4) Part d

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.05$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

And replacing into equation (b) the values from part a we got:

$n=\frac{0.42(1-0.42)}{(\frac{0.05}{2.58})^2}=648.599$

And rounded up we have that n=649

5 0

3 years ago

Todd earned some money doing chores. He spent one-fourth of his money see a movie. Then he spent $6.00 on popcorn and drinks. Wh

Vsevolod [243]

Answer: Todd earned $40 mowing the neighbor's lawn.

Step-by-step explanation:

Let x represent the amount of money that Todd earned, mowing his neighbor's lawn.

He spent one-fourth of his money see a movie. It means that the amount spent in seeing a movie is x/4

Then he spent $6.00 on popcorn and drinks. It means that the total amount spent is

x/4 + 6

The amount left would be

x - (x/4 + 6) = x - x/4 - 6

When he went home, he had $24.00 left. It means that

x - x/4 - 6 = 24

x - x/4 = 24 + 6

x - x/4 = 30

Cross multiplying by 4, it becomes

4x - x = 120

3x = 120

x = 120/3

x = $40

7 0

3 years ago

Does anyone know how to do this?

sineoko [7]

Answer:

$\boxed{\tt x=\sqrt{85} }$

Step-by-step explanation:

When making a right triangle with 2 points, the distance is the hypotenuse which can be represent as "x"

To find the distance we can use the Pythagorean theorem.

$\boxed{{\tt a^2+b^2=c^2}}$

→ $\tt a=9$

→ $\tt b=2$

→ $\tt c=x$

Let's Plug in the side lengths:

$\tt 9^2+2^2=x^2$

Evaluate 9²= 81 and 2²= 4:

$\tt 81+4=x^2$

Now, add 81+4= 85

$\tt 85=x^2$

Take the square root of both sides:

$\tt x=\sqrt{85}$

_____________________________

5 0

2 years ago