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3 years ago

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The 12th term of the arithmetic sequence is 10.5. The 18th term of this sequence is 13.5. Find the common difference and the fir

st term

1 answer:

xxMikexx [17]3 years ago

7 0

Answer:

common difference is 0.5

first term is 5

Step-by-step explanation:

<em>use </em><em>the </em><em>formula</em><em> for</em><em> </em><em>the</em><em> </em><em>nth </em><em>term </em><em>of </em><em>an </em><em>ap </em><em>Tn=</em><em>a+</em><em>(</em><em>n-1)</em><em>d</em>

<em>T12=</em><em>1</em><em>0</em><em>.</em><em>5</em>

<em>T18=</em><em>1</em><em>3</em><em>.</em><em>5</em>

<em>therefore</em><em> </em><em>come </em><em>up </em><em>with </em><em>two </em><em>equations</em>

<em>T12=</em><em>a+</em><em>(</em><em>1</em><em>2</em><em>-</em><em>1</em><em>)</em><em>d</em>

<em>1</em><em>0</em><em>.</em><em>5</em><em>=</em><em>a+</em><em>1</em><em>1</em><em>d</em><em>(</em><em>1</em><em>s</em><em>t</em><em> </em><em>equation</em><em>)</em>

<em>T18</em><em>=</em><em>a+</em><em>(</em><em>1</em><em>8</em><em>-</em><em>1</em><em>)</em><em>d</em>

<em>1</em><em>3</em><em>.</em><em>5</em><em>=</em><em>a+</em><em>1</em><em>7</em><em>d</em><em>(</em><em>2</em><em>n</em><em>d</em><em> </em><em>equation</em><em>)</em>

<em>then </em><em>solve </em><em>both </em><em>as </em><em>a </em><em>simultaneous</em><em> </em><em>equation</em>

<em>a+</em><em>1</em><em>1</em><em>d</em><em>=</em><em>1</em><em>0</em><em>.</em><em>5</em>

<em>a+</em><em>1</em><em>7</em><em>d</em><em>=</em><em>1</em><em>3</em><em>.</em><em>5</em>

<em> </em><em> </em><em> </em><em> </em><em>-6d/</em><em>-</em><em>6</em><em>=</em><em>-</em><em>3</em><em>/</em><em>-</em><em>6</em>

<em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em> </em><em>d=</em><em>0</em><em>.</em><em>5</em>

<em>use </em><em>one </em><em>of</em><em> the</em><em> </em><em>equations</em><em> </em><em>to </em><em>find </em><em>the </em><em>first</em><em> </em><em>term</em>

<em>a+</em><em>1</em><em>1</em><em>(</em><em>0</em><em>.</em><em>5</em><em>)</em><em>=</em><em>1</em><em>0</em><em>.</em><em>5</em>

<em>a+</em><em>5</em><em>.</em><em>5</em><em>=</em><em>1</em><em>0</em><em>.</em><em>5</em>

<em>a=</em><em>1</em><em>0</em><em>.</em><em>5</em><em>-</em><em>5</em><em>.</em><em>5</em>

<em>a=</em><em>5</em>

<em>I </em><em>hope </em><em>this </em><em>helps</em>

<em>please </em><em>mark</em><em> </em><em>as </em><em>brainliest</em>

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Step-by-step explanation:

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3 years ago

Point B has coordinates (1,2). The x-coordinate of point A is -8. The distance between point A and point B is 15 units. What

Xelga [282]

Answer:

The possible coordinates of point A are $A_{1} (x,y) = (-8, 14)$ and $A_{2} (x,y) = (-8, -10)$ , respectively.

Step-by-step explanation:

From Analytical Geometry, we have the Equation of the Distance of a Line Segment between two points:

$l_{AB} = \sqrt{(x_{B}-x_{A})^{2} + (y_{B}-y_{A})^{2}}$ (1)

Where:

$l_{AB}$ - Length of the line segment AB.

$x_{A}, x_{B}$ - x-coordinates of points A and B.

$y_{A}, y_{B}$ - y-coordinates of points A and B.

If we know that $l_{AB} = 15$ , $x_{A} = -8$ , $x_{B} = 1$ and $y_{B} = 2$ , then the possible coordinates of point A is:

$\sqrt{(1+8)^{2}+(2-y_{A})^{2}} = 15$

$81 + (2-y_{A})^{2} = 225$

$(2-y_{A})^{2} = 144$

$2-y_{A} = \pm 12$

There are two possible solutions:

1) $2-y_{A} = -12$

$y_{A} = 14$

2) $2 - y_{A} = 12$

$y_{A} = -10$

The possible coordinates of point A are $A_{1} (x,y) = (-8, 14)$ and $A_{2} (x,y) = (-8, -10)$ , respectively.

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3 years ago

Two cars got an oil change at the same auto shop. The shop charges customers for each quart of oil plus a flat fee for labor. Th

zvonat [6]

The labor fee is $13.55 and each quart of oil is $2.25

Step-by-step explanation:

Let,

x be the amount of each quart of oil

y be the amount of labor fee

According to given statement;

5x+y=24.80 Eqn 1

7x+y=29.30 Eqn 2

Subtracting Eqn 1 from Eqn 2

$(7x+y)-(5x+y)=29.30-24.80\\7x+y-5x-y=4.50\\2x=4.50$

Dividing both sides by 2

$\frac{2x}{2}=\frac{4.50}{2}\\x=2.25$

Putting x=2.25 in Eqn 1

$5(2.25)+y=24.80\\11.25+y=24.80\\y=24.80-11.25\\y=13.55$

The labor fee is $13.55 and each quart of oil is $2.25

Keywords: linear equation, subtraction

Learn more about subtraction at:

#LearnwithBrainly

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3 years ago

Mrs. Wilkerson cut some oranges into 20 equal pieces to be shared by 6 friends. How many pieces did each person get and how many

n200080 [17]

Each friend got 3 and there were 2 pieces left over, to find the answer you would do the following:

20/6 (20 divided by six) which is 18 and the remainder is 2

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3 years ago

Read 2 more answers

In a rectangle ABCD if AB=4x and DC=7x-9,find the length of AB.(Lengths are in cm).

myrzilka [38]

Answer:

12 cm

Step-by-step explanation:

AB and DC are parallel to each other, so they are the same length. Set their lengths equal to each other and solve for x

4x = 7x - 9

4x - 7x = 7x - 7x -9

-3x = -9

-3x/-3 = -9/-3

x = 3

Now solve for AB.

AB = 4x

AB = 4(3)

AB = 12

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2 years ago