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3 years ago

Select the correct answer, and simplify the expression -3÷(-2/5). A. -7 1/2

Mathematics

1 answer:

aliina [53]3 years ago

3 0

Answer:

Step-by-step explanation:

Given

- 3 ÷ - $\frac{2}{5}$

Leave the first number, change division to multiplication and turn the fraction upside down, that is

= - 3 × - $\frac{5}{2}$

= $\frac{3(5)}{2}$

= $\frac{15}{2}$

= 7 $\frac{1}{2}$ → D

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Please help with this question!! I need serious help!!

asambeis [7]

Answer:

<h2>The circumference is multipled by 4.</h2>

Step-by-step explanation:

The formula of an area of a circle"

$A=\pi r^2$

The formula of a circumference of a circle:

$C=2\pi r$

The area multipled by 16:

$16A=16\pi r^2\\\\16A=\pi(4^2r^2)\\\\16A=\pi(4r)^2$

The radius has increased fourfold, therefore:

$C'=2\pi(4r)=4(2\pi r)=4C$

The circumference is multipled by 4.

You can calculate the area and check the circumference:

$r=11.6\ in\\\\A=\pi(11.6)^2=132.56\pi\\\\16A=(16)(134.56\pi)=2152.96\pi\ in^2$

Calculate the radius:

$\pi r^2=2152.96\pi$ <em>divide both sides by π</em>

$r^2=2152.96\to r=\sqrt{2152.96}\\\\r=46.4\ in$

Calculate the circumference of both circles:

$r=11.6\ in\\\\C=2\pi(11.6)=23.2\pi\ in$

$r=46.4\ in\\\\C'=2\pi(46.4)=92.8\pi\ in$

$\dfrac{C'}{C}=\dfrac{92.8\pi}{23.2\pi}=4\to C'=4C$

5 0

2 years ago

Simplify: cos2x-cos4 all over sin2x + sin 4x

GrogVix [38]

Answer:

$\frac{\cos\left(2x\right)-\cos\left(4x\right)}{\sin\left(2x\right)+\sin\left(4x\right)}=\tan\left(x\right)$

Step-by-step explanation:

$\frac{\cos\left(2x\right)-\cos\left(4x\right)}{\sin\left(2x\right)+\sin\left(4x\right)}$

Apply formula:

$\cos\left(A\right)-\cos\left(B\right)=-2\cdot\sin\left(\frac{A+B}{2}\right)\cdot\sin\left(\frac{A-B}{2}\right)$ and

$\sin\left(A\right)+\sin\left(B\right)=2\cdot\sin\left(\frac{A+B}{2}\right)\cdot\sin\left(\frac{A-B}{2}\right)$

We get:

$=\frac{-2\cdot\sin\left(\frac{2x+4x}{2}\right)\cdot\sin\left(\frac{2x-4x}{2}\right)}{2\cdot\sin\left(\frac{2x+4x}{2}\right)\cdot\cos\left(\frac{2x-4x}{2}\right)}$

$=\frac{-\sin\left(\frac{2x-4x}{2}\right)}{\cos\left(\frac{2x-4x}{2}\right)}$

$=\frac{-\sin\left(\frac{-2x}{2}\right)}{\cos\left(\frac{-2x}{2}\right)}$

$=\frac{-\sin\left(-x\right)}{\cos\left(-x\right)}$

$=\frac{-\cdot-\sin\left(x\right)}{\cos\left(x\right)}$

$=\frac{\sin\left(x\right)}{\cos\left(x\right)}$

$=\tan\left(x\right)$

Hence final answer is

$\frac{\cos\left(2x\right)-\cos\left(4x\right)}{\sin\left(2x\right)+\sin\left(4x\right)}=\tan\left(x\right)$

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2 years ago

Sisters math question

zalisa [80]

Answer:

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Step-by-step explanation:

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2 years ago

What is the answer to:<br> -4(2x+2) <-40

mars1129 [50]

Answer: x > 6

Step-by-step explanation: -4(2x+2) < -40

-8x - 8 < -40

+8 +8

-8x < 48

/-8x /-8x

x > 6 *The less than sign got flipped to a greater than sign because we divided by a negative.

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1 year ago

If Steve throws the football 50 meters in 3 seconds, what is the average speed of the football? Speed = distance / time

ankoles [38]

Answer:

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2 years ago

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