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4 years ago

. Multiply (x + 3)(x – 3).

1 answer:

8 0

X × x = x^2
x × -3 = -3x
3 × x = 3x
3 × -3 = -9

x^2 + 3x - 3x - 9
So I would agree with C because the -3x and the 3x cancel each other out. I hope this helps!

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Derive these identities using the addition or subtraction formulas for sine or cosine: sinacosb=(sin(a+b)+sin(a-b))/2

Sergeu [11.5K]

Answer:

The work is in the explanation.

Step-by-step explanation:

The sine addition identity is:

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

The sine difference identity is:

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

The cosine addition identity is:

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

The cosine difference identity is:

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

We need to find a way to put some or all of these together to get:

$\sin(a)\cos(b)=\frac{\sin(a+b)+\sin(a-b)}{2}$ .

So I do notice on the right hand side the $\sin(a+b)$ and the $\sin(a-b)$ .

Let's start there then.

There is a plus sign in between them so let's add those together:

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

$=[\sin(a+b)]+[\sin(a-b)]$

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

There are two pairs of like terms. I will gather them together so you can see it more clearly:

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

$=2\sin(a)\cos(b)+0$

$=2\sin(a)\cos(b)$

So this implies:

$\sin(a+b)+\sin(a-b)=2\sin(a)\cos(b)$

Divide both sides by 2:

$\frac{\sin(a+b)+\sin(a-b)}{2}=\sin(a)\cos(b)$

By the symmetric property we can write:

$\sin(a)\cos(b)=\frac{\sin(a+b)+\sin(a-b)}{2}$

3 0

3 years ago

Adrian took out a simple interest loan for $2000. The rate on this loan is 7% and he will pay it back in 5 years. How much money

laila [671]

Answer:

i think its 700

Step-by-step explanation:

7%of 2000 is 140 and 140 x 5 is 700

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3 years ago

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Irina18 [472]

By the second day of growth

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3 years ago

20 red marbles to 40 blue marbles (ratio as a fraction)

Tanya [424]

Answer:

20/40 = 10/20 = 1/2, 1:2

Step-by-step explanation:

I hope this helped and if it did I would appreciate it if you marked me Brainliest. Thank you and have a nice day!

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Describe the next figure in each pattern. Then draw the figure

madreJ [45]

The first figure has 3 angles, the second one has 4 angles, the third one has 5 angles so the next one will have 6 angles.

The violet figures inside stick with each side of the outer figures in the middle, so the last figure will look more less like in the attachment.

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