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Galina-37 [17]
3 years ago
9

The sum of twice a number and 7 is -19

Mathematics
2 answers:
Neporo4naja [7]3 years ago
8 0

Answer:

The number is:

-13

Step-by-step explanation:

2a+7 = -19

2a = -19 -7

2a = -26

a = -26/2

a = -13

Check:

2*-13 + 7 = -19

-26 + 7 = -19

adoni [48]3 years ago
4 0

Answer:

The number will be -13

Step-by-step explanation:

Let the no. be x

Its twice will be = 2x

According to the question ,

2x + 7 = -19\\=> 2x = -19 - 7 = -26\\=> x = \frac{- 26}{2} = - 13

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Find constants a and b such that the function y = a sin(x) + b cos(x) satisfies the differential equation y'' + y' − 7y = sin(x)
Elza [17]
The first thing we must do in this case is find the derivatives:
 y = a sin (x) + b cos (x)
 y '= a cos (x) - b sin (x)
 y '' = -a sin (x) - b cos (x)
 Substituting the values:
 (-a sin (x) - b cos (x)) + (a cos (x) - b sin (x)) - 7 (a sin (x) + b cos (x)) = sin (x)
 We rewrite:
 (-a sin (x) - b cos (x)) + (a cos (x) - b sin (x)) - 7 (a sin (x) + b cos (x)) = sin (x)
 sin (x) * (- a-b-7a) + cos (x) * (- b + a-7b) = sin (x)
 sin (x) * (- b-8a) + cos (x) * (a-8b) = sin (x)
 From here we get the system:
 -b-8a = 1
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 Whose solution is:
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4 0
3 years ago
Just need help on #7 thru 8(a), b and c
Stella [2.4K]

7

a. The slope of the line passing through the points R(3, 5) and H(-1,2) is -3/4

b. The distance between two points (x₁, y₁) and (x₂,y₂) is 5 units

c.  The midpoint of the R(3, 5) and H(-1,2) is  (2, 4)

8.

a. The transformation rule is  (x,y) → (x + 1, y - 1)

b.

  • The x-coordinate is shifted 1 unit to the left and
  • The y - coordinate is shifted 1 unit downwards.

c. The image of B' the pre-image of B(5, 6) is (6, 5)

<h3 /><h3>7 a. How to find the slope of the line?</h3>

The slope of a line passing through the points (x₁, y₁) and (x₂,y₂) is m = (y₂ - y₁)/(x₂ - x₁)

Given that

  • (x₁, y₁) = (3, 5) and
  • (x₂,y₂) = (-1, 2)

So, m = (y₂ - y₁)/(x₂ - x₁)

m = (2 - 5)/(-1 - 3)

m = -3/-4

m = -3/4

So, the slope of the line passing through the points R(3, 5) and H(-1,2) is -3/4

<h3>b. The distance between the points</h3>

The distance between two points (x₁, y₁) and (x₂,y₂) is d = √[(y₂ - y₁)² + (x₂ - x₁)²]

Given that

  • (x₁, y₁) = (3, 5) and
  • (x₂,y₂) = (-1, 2)

d = √[(y₂ - y₁)² + (x₂ - x₁)²]

d = √[(2 - 5)² + (-1 - 3)²]

d = √[(-3)² + (-4)²]

d = √[9 + 16]

d = √25

d = 5 units

So, the distance between two points (x₁, y₁) and (x₂,y₂) is 5 units

<h3>7 c How to find the midpoint of the R(3, 5) and H(-1,2) </h3>

The midpoint of the the points (x₁, y₁) and (x₂,y₂) is (x, y)  = [(x₁ + x₂)/2, (y₁ + y₂)/2]

Given that

  • (x₁, y₁) = (3, 5) and
  • (x₂,y₂) = (-1, 2)

So, the midpoint (x, y)  = [(x₁ + x₂)/2, (y₁ + y₂)/2]

(x, y)  = [(3 + (-1))/2, (5 + 3)/2]

(x, y)  = [(3 - 1)/2, (5 + 3)/2]

(x, y)  = [4/2, 8/2]

(x, y)  = (2, 4)

So, the midpoint of the R(3, 5) and H(-1,2) is  (2, 4)

<h3>8. a The rule for the transformation of point A(1, 4) to point B(2, 3)</h3>

Given that point A(1, 4) and point B(2, 3) we see that point B(1 + 1, 4 - 1).

Let pont A be (x,y).

So, point B = (x + 1, y - 1)

So, the transformation rule is  (x,y) → (x + 1, y - 1)

<h3>b. Describe the transformation</h3>

Since the transformation rule is   (x,y) → (x + 1, y - 1), we see that

  • the x-coordinate is shifted 1 unit to the left and
  • the y - coordinate is shifted 1 unit downwards.
<h3>c. The image of B' the pre-image of B(5, 6)</h3>

Since the transformation rule is  (x,y) → (x + 1, y - 1) and point B is (5, 6), thus the image of B' is

(x,y) → (x + 1, y - 1)

(5,6) → (5 + 1, 6 - 1)

(5,6) → (6, 5)

So, the image of B' the pre-image of B(5, 6) is (6, 5)

Learn more about slope of a line here:

brainly.com/question/1617757

#SPJ1

3 0
2 years ago
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grigory [225]

Answer:

10. 7n - 1 < -8

Isolate the variable, n. Do the opposite of PEMDAS. Treat the < as equal sign, what you do to one side, you do to the other. First, add 1 to both sides:

7n - 1 (+1) < - 8 (+1)

7n < - 8 + 1

7n < - 7

Isolate the variable, n. Divide 7 from both sides:

(7n)/7 < (-7)/7

n < -7/7

n < -1

n < -1 is your answer.

11. 3 > -7v + 4v

Combine like terms, then isolate the variable, v. First, add -7v and 4v together.

3 > (-7v + 4v)

3 > (4v - 7v)

3 > (-3v)

Isolate the variable, v. Divide -3 from both sides. Note that since you are dividing a negative number, you must flip the sign:

(3)/-3 > (-3v)/-3

3/-3 > v

-1 < v

v > -1 is your answer.

~

4 0
3 years ago
Tom had 216 marbles. First, he divided them into 3 equal groups. Then he put two groups into a 2 separate bags. He took the rema
Dahasolnce [82]

Answer: each of his friends got 24 marbles

Step-by-step explanation:

216 / 3 = 72

72 / 3 = 24

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3 years ago
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How did you get that answer j
gtnhenbr [62]

i answer the questions that relate to the lessons i've learned

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