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3 years ago

I need help with letter C, find the area

Mathematics

1 answer:

ElenaW [278]3 years ago

5 0

Answer:

x = 38

Step-by-step explanation:

Here, we can use the area formula A = 0.5(Bh) to solve for x.

In this case, A = 399, B = x, and h = 21

$399 = \frac{21}{2} x\\x = \frac{2*399}{21} \\x = 38$

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Help pls my test is about to end

lara31 [8.8K]

Answer:

rule is when x increases by 1, y decreases by 3000

Step-by-step explanation:

6 0

3 years ago

Solve for x in the equation 3 x squared minus 18 x + 5 = 47.

Lana71 [14]

Answer:

first option

Step-by-step explanation:

3x² - 18x + 5 = 47 ( subtract 5 from both sides )

3x² - 18x = 42 ( divide through by 3 )

x² - 6x = 14

Using the method of completing the square

add ( half the coefficient of the x- term )² to both sides

x² + 2(- 3)x + 9 = 14 + 9

(x - 3)² = 23 ( take square root of both sides )

x - 3 = ± $\sqrt{23}$ ( add 3 to both sides )

x = 3 ± $\sqrt{23}$

6 0

3 years ago

Integration of dx/3sin^2 -4

Scilla [17]

Answer:

= 1/2 tan^(-1)(2 cot(x)) + constant

Step-by-step explanation:

Take the integral:

integral1/(3 sin^2(x) - 4) dx

Multiply numerator and denominator of 1/(3 sin^2(x) - 4) by -sec^2(x):

= integral-(sec^2(x))/(4 sec^2(x) - 3 tan^2(x)) dx

Prepare to substitute u = tan(x). Rewrite -(sec^2(x))/(4 sec^2(x) - 3 tan^2(x)) using sec^2(x) = tan^2(x) + 1:

= integral-(sec^2(x))/(tan^2(x) + 4) dx

For the integrand -(sec^2(x))/(tan^2(x) + 4), substitute u = tan(x) and du = sec^2(x) dx:

= integral-1/(u^2 + 4) du

Factor out constants:

= - integral1/(u^2 + 4) du

Factor 4 from the denominator:

= - integral1/(4 (u^2/4 + 1)) du

Factor out constants:

= -1/4 integral1/(u^2/4 + 1) du

For the integrand 1/(u^2/4 + 1), substitute s = u/2 and ds = 1/2 du:

= -1/2 integral1/(s^2 + 1) ds

The integral of 1/(s^2 + 1) is tan^(-1)(s):

= -1/2 tan^(-1)(s) + constant

Substitute back for s = u/2:

= -1/2 tan^(-1)(u/2) + constant

Substitute back for u = tan(x):

= -1/2 tan^(-1)(tan(x)/2) + constant

Which is equivalent for restricted x values to:

Answer: = 1/2 tan^(-1)(2 cot(x)) + constant

6 0

3 years ago

I need help from people that know the answer is right!!PLEASE HELP ASAP

nikdorinn [45]

Radius=r=3ft

Its a sphere

$\boxed{\sf Volume=\dfrac{4}{3}πr^3}$

$\\ \sf\longmapsto Volume=\dfrac{4}{3}\times\dfrac{22}{7}\times 3^3$

$\\ \sf\longmapsto Volume=\dfrac{4\times 22}{7}\times 9$

$\\ \sf\longmapsto Volume=113.1ft^3$

5 0

3 years ago

two planes, which are 1965 miles apart, fly toward each other. their speeds differ by 55mph. if they pass each other other in 3

Alexus [3.1K]

The speed of the planes are 300 miles per hour and 355 miles per hour.

<u>Solution:</u>

Given, Two planes are 1965 miles apart, flying toward each other.

Their speeds differ by 55 mph.

They pass each other in 3 hours,

We have to find what is the speed of each?

Let the speed of 1st plane be s miles per hour, then speed of the other plane will be s + 55 miles per hour.

And, distance travelled by 1st plane be d, then distance travelled by other plane will be 1965 – d miles

Now, we know that, distance = speed $\times$ time

So, for 1st plane ⇒ $\mathrm{d}=\mathrm{s} \times 3$

For 2nd plane ⇒ $1965-d=(s+55) \times 3$

By using 1st plane equation

1965 – 3s = 3s + 165

1965 – 165 = 3s + 3s

6s = 1800

s = 300

So, speed of 1st plane is 300 miles per hour, then speed of 2nd plane will be 300 + 55 = 355 miles per hour.

Hence, the speed of the planes are 300 miles per hour and 355 miles per hour.

4 0

4 years ago