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Nataly_w [17]
2 years ago
15

In an arithmetic sequence, a3=15 and a8=0. What is the value of a5?

Mathematics
1 answer:
Nina [5.8K]2 years ago
7 0

Answer:

a3=15 , n=3

a8=0, n=8

a5 = ?

an = a1+ (n-1)d

a3 = a1 + (3-1) d

a3=a1+2d

and a8 = a1 + (8-1 )d

a8= a1+ 7d

15 = a1 + 2 d-------1

0= a1 +7 d----------2

substacting eq 2 from eq 1

15= - 5d

- 5d = 15

divide by - 5

d = -3

putting the value of d in eq 1

15 = a1 + 7 (-3)

15 = a1 -21

adding 21 on both sides

a1-21+21= 15+21

a1 = 36

a5 = ?, n=5, d= -3, a1=36

a5 = 36 + (5-1) (-3)

= 36+(4)(-3)

= 36-12

= 24

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coldgirl [10]

Answer:

Tamara incorrectly factored the whole expression.

Step-by-step explanation:

Note that

•21x=3·7·x;

•56xy=2·2·2·7·x·y.

Mark in bold all common factors, then GCF(21x,56xy)=7·x=7x.

Thus,

21x+56xy=7x(3+8y).

Hence, Tamara correctly found the GCF of numbers 21 and 56, but incorrectly factored the whole expression.

6 0
2 years ago
the second term of a geometric sequence is 18 and the fourth term is 8 find the common ratio . And find the sum of the first 6 t
777dan777 [17]

Answer:

  • ratio: 2/3
  • sum: 73 8/9

Step-by-step explanation:

The general term of a geometric sequence is ...

  an = a1·r^(n-1)

You have the 2nd and 4th terms, so ...

  a2 = a1·r^(2-1) = a1·r

  a4 = a1·r^(4-1) = a1·r^3

We can find r from the ratio ...

  a4/a2 = (a1·r^3)/(a1·r) = r^2 = 8/18 = 4/9

Then r is ...

  r = √(4/9) = 2/3 . . . . the common ratio

The first term is ...

  a2 = 18 = a1·(2/3)

  a1 = (3/2)·18 = 27

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The sum of the first 6 terms is ...

  Sn = a1·(r^n -1)/(r -1)

  S6 = 27·((2/3)^6 -1)/(2/3 -1)

  S6 = 27·(64/729-1)/(2/3-1) = (27)(665)/243 = 73 8/9

The sum of the first 6 terms is 73 8/9.

_____

<em>Check on the sum</em>

The first 6 terms are ...

  27, 18, 12, 8, 5 1/3, 3 5/9

Their sum is 73 8/9, as above.

8 0
3 years ago
3. What are the intersection points of the line whose equation is y=3x +3 and the
densk [106]

Answer:

Points of intersection of these graphs are (-2, -3) and (0.6, 4.8).

Step-by-step explanation:

Equation of the circle → (x - 2)² + y² = 25 ---------(1)

                                   → (x - 2)² + (y - 0)² = 5²

By comparing this equation with the standard equation of the circle,

(x - a)² + (y - b)²= r²

Here (a, b) is the center and r is the radius of the circle.

Therefore, center of the circle is (2, 0) and radius = 5 units

Second equation is a linear equation → y = 3x + 3 -------(2)

x-intercept of the equation → x = -1

y-intercept of the equation → y = 3

By graphing these equations we can get the point of intersections.

Solving these equations algebraically,

Substitute the value of y from equation (2) in the equation (1),

(x - 2)² + (3x + 3)² = 25

x² - 4x + 4 + 9x² + 18x + 9 = 25

10x² + 14x - 12 = 0

5x² + 7x - 6 = 0

x = \frac{-7\pm \sqrt{7^2-4(5)(-6)}}{2(5)}

x = \frac{-7\pm \sqrt{169}}{10}

x = \frac{-7\pm13}{10}

x = -2, 0.6

From equation (2),

y = -3, 4.8

Therefore, points of intersection of these graphs are (-2, -3) and (0.6, 4.8).

6 0
3 years ago
Given the statement -12 ≤ -15, which of the following is correct? It is a false statement, because -12 is not equal to -15. It i
laiz [17]

The given statement is a false statement because -12 is not equal to -15 and also -15 is less than -12 which are correct answers would be Options (A) and (D).

<h3>What is inequality?</h3>

Inequality is defined as mathematical statements that have a minimum of two terms containing variables or numbers that are not equal.

The given statement as:

⇒ -12 ≤ -15

Since -12 and -15 are not equal and -15 is smaller than -12, the preceding statement is incorrect.

So the following statements are correct:

It is a false statement because -12 is not equal to -15.

It is a false statement because -15 is less than -12.

Hence, the given statement is a false statement because -12 is not equal to -15 and also -15 is less than -12 which are correct answers would be Options (A) and (D).

Learn more about the inequality here :

brainly.com/question/20383699

#SPJ1

5 0
2 years ago
PLEASE PLEASE HELP ME
mina [271]
The answer is <EKF and <HKI
3 0
3 years ago
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