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3 years ago

1/9 of people in a class are left handed.

Mathematics

1 answer:

LenaWriter [7]3 years ago

3 0

Answer:

left handed: right handed

1 : 8

Step-by-step explanation:

1 out of every 9 people are left handed

9-1 = 8

That means 8 of the 9 are right handed

left handed: right handed

1 : 8

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Juanita is having a party at her house she is inviting 12 people.there will be 3 times as many boys as girls invited. let x repr

Margaret [11]

X + 3x = 12

(Or 4x=12)

the first x is the number of girls then the second x is the girls times 3, which is how many boys there are.

8 0

3 years ago

The mean score of a placement exam for entrance into a math class is 80, with a standard deviation of 10. Use the empirical rul

Sedbober [7]

Answer:

47.5%

Step-by-step explanation:

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3 years ago

Rewrite with only sin x and cos x.

Annette [7]

Option A

$\cos 3 x=\cos x-4 \cos x \sin ^{2} x$

<em><u>Solution:</u></em>

Given that we have to rewrite with only sin x and cos x

Given is cos 3x

$cos 3x = cos(x + 2x)$

We know that,

$\cos (a+b)=\cos a \cos b-\sin a \sin b$

Therefore,

$\cos (x+2 x)=\cos x \cos 2 x-\sin x \sin 2 x$ ---- eqn 1

We know that,

$\sin 2 x=2 \sin x \cos x$

$\cos 2 x=\cos ^{2} x-\sin ^{2} x$

Substituting these values in eqn 1

$\cos (x+2 x)=\cos x\left(\cos ^{2} x-\sin ^{2} x\right)-\sin x(2 \sin x \cos x)$ -------- eqn 2

We know that,

$\cos ^{2} x-\sin ^{2} x=1-2 \sin ^{2} x$

Applying this in above eqn 2, we get

$\cos (x+2 x)=\cos x\left(1-2 \sin ^{2} x\right)-\sin x(2 \sin x \cos x)$

$\begin{aligned}&\cos (x+2 x)=\cos x-2 \sin ^{2} x \cos x-2 \sin ^{2} x \cos x\\\\&\cos (x+2 x)=\cos x-4 \sin ^{2} x \cos x\end{aligned}$

$\cos (x+2 x)=\cos x-4 \cos x \sin ^{2} x$

Therefore,

$\cos 3 x=\cos x-4 \cos x \sin ^{2} x$

Option A is correct

7 0

3 years ago

A drone has an effective range represented by a circle on a coordinate plane. The points (–12, 3) and (–6, –5) are endpoints of

Mrac [35]

Answer:

(x+9)^2 + (y+1)^2 = 100

Step-by-step explanation:

Since the question says diameter, we know the boundary in a circle. Therefore, we just need to find the center and radius.

The center is the midpoint of the two endpoints on a diameter.

Here, it is (-9, -1).

Therefore, the left part of the equation is (x- -9)^2 + (y - -1)^2 = (x+9)^2 + (y+1)^2.

The radius: sqrt(8^2 + 6^2) = 10

So the equation is (x+9)^2 + (y+1)^2 = 100

3 0

3 years ago

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Josiah used the distributive property to simplify the multiplication problem 9 × 4.7. Which of the following statements is true

zaharov [31]

Answer:

E. he multiplied 9 and 0.7 incorrectly.

Step-by-step explanation:

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3 years ago