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Sergeu [11.5K]
3 years ago
12

Evaluate the following expression. 1−4x(-3)+8x(-3)

Mathematics
1 answer:
Ira Lisetskai [31]3 years ago
7 0

Answer: 1- 12x

Step-by-step explanation:

Step 1- open bracket and mind the signs

1−4x(-3)+8x(-3)

1+12x-24x

1-12×

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B is the midpoint of ac. Ab = x+9 and bc = 3x-7 find x and ac
natali 33 [55]

To solve this problem, we need to know 2 relationships:

<h2>1. AC = AB + BC</h2>

The distance of AC is the sum of AB and BC.

AC = AB + BC

We know this since the distance of going from A to C (AC) is the same as going from A to B (AB), then B to C (BC).

<h2>2. AB = BC</h2>

The distance of AB is the same as AC.

AB = BC

We know this since B is in the middle of AC, so the distance from B to A (BA) is the same as the distance from B to C (BC).

You can see the attached image (at the bottom) for a visualization of this.

<h2>Putting them together</h2>

Since we know the values of AB and BC...

AB = x+9\\BC = 3x-7

...we can put these values into our 2nd equation and solve for x:

AB = BC\\x + 9 = 3x -7

Add 7 to both sides:

x + 16 = 3x

Subtract x from both sides:

16 = 2x

Divide both sides by 2:

8 = x\\x = 8

Knowing x, we can find the distance of AC using our first equation.

AC = AB + BC

Let's put in the values of AB and BC:

AC = (x+9) + (3x-7)

Before we put in x = 8, we can simplify this:

AC = (x+9) + (3x-7)\\AC = x + 9 + 3x -7\\AC = x + 3x + 9 -7\\AC = 4x + 9 - 7\\AC = 4x+2

We group x and 3x and add those together. Then we subtract 7 from 9.

With this equation, we can put in x = 8:

AC = 4x +2\\AC = 4*8 + 2

Since 4 * 8 = 32:

AC = 4 * 8 + 2\\AC = 32 + 2\\AC = 34

Finally, we have found both x and AC.

<h2>Answer</h2>

x = 8

AC = 34

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4 years ago
1 pound of apples for $2.15 or 3 pounds of apples for $5.76
ollegr [7]

Answer:$7.91


Step-by-step explanation:add 2.15+5.76=7.91


7 0
3 years ago
A rainwater collection barrel has the dimensions shown.
Kipish [7]

Answer:

56

Step-by-step explanation:

if it is lenght by width then you would multiply the two numbers

8 0
3 years ago
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What is 574 ÷ 82 my math say use compatible numbers to round first then awnser the actual queston
Svetradugi [14.3K]

Answer: 7               explanation:574%%82=7  7x82=574

7 0
3 years ago
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Futhe Mathematics<br><img src="https://tex.z-dn.net/?f=%28Cos%20%7B%7D%5E%7B4%7Dt%20-Sin%20%7B%7D%5E%7B4%7Dt%20%29%20%20%5Cdiv%2
Nastasia [14]

Answer:

cos2t/cos²t

Step-by-step explanation:

Here the given trigonometric expression to us is ,

\longrightarrow \dfrac{cos^4t - sin^4t }{cos^2t }

We can write the numerator as ,

\longrightarrow \dfrac{ (cos^2t)^2-(sin^2t)^2}{cos^2t }

Recall the identity ,

\longrightarrow (a-b)(a+b)=a^2-b^2

Using this we have ,

\longrightarrow \dfrac{(cos^2t + sin^2t)(cos^2t-sin^2t)}{cos^2t}

Again , as we know that ,

\longrightarrow sin^2\phi + cos^2\phi = 1

Therefore we can rewrite it as ,

\longrightarrow \dfrac{1(cos^2t - sin^2t)}{cos^2t}

Again using the first identity mentioned above ,

\longrightarrow \underline{\underline{\dfrac{(cost + sint )(cost - sint)}{cos^2t}}}

Or else we can also write it using ,

\longrightarrow cos2\phi = cos^2\phi - sin^2\phi

Therefore ,

\longrightarrow \underline{\underline{\dfrac{cos2t}{cos^2t}}}

And we are done !

\rule{200}{4}

Additional info :-

<em>D</em><em>e</em><em>r</em><em>i</em><em>v</em><em>a</em><em>t</em><em>i</em><em>o</em><em>n</em><em> </em><em>o</em><em>f</em><em> </em><em>c</em><em>o</em><em>s</em><em>²</em><em>x</em><em> </em><em>-</em><em> </em><em>s</em><em>i</em><em>n</em><em>²</em><em>x</em><em> </em><em>=</em><em> </em><em>c</em><em>o</em><em>s</em><em>2</em><em>x</em><em> </em><em>:</em><em>-</em>

We can rewrite cos 2x as ,

\longrightarrow cos(x + x )

As we know that ,

\longrightarrow cos(y + z )= cosy.cosz -  siny.sinz

So that ,

\longrightarrow cos(x+x) = cos(x).cos(x) - sin(x)sin(x)

On simplifying,

\longrightarrow cos(x+x) = cos^2x - sin^2x

Hence,

\longrightarrow\underline{\underline{cos (2x) = cos^2x - sin^2x }}

\rule{200}{4}

7 0
2 years ago
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