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3 years ago

Solve the following pairs of simultaneous equations.

Mathematics

1 answer:

Sergeeva-Olga [200]3 years ago

3 0

Answer and step-by-step explanation:

a) -4x + 5y = -9 (2)

2x + 3y = 21

Multiply the second equation by 2, you will get:

4x + 6y = 42 (1)

Use (1) plus with (2), you will get:

4x + (-4x) + 6y + 5y = -9 + 42

11y = 33

y = 33/11

y = 3

4x + 18 = 42

4x = 24

x = 6

b) 2x + 5y = -6

3x + 2y = 2

Multiply first equation by 3, you will get:

6x + 15y = -18 (1)

Multiply the second equation by 2 and you will get:

6x + 4y = 4 (2)

Subtract (1) by (2), we got:

6x -6x + 15y - 4y = -18 - 4

11y = -22

y = -22/11

y = -2

6x + 4y = 4

6x -8 = 4

6x = 12

x = 2

c) 2x - 2y = -4

5x + 4y = 17 (2)

Multiply the first euation by 2, we got:

4x - 4y = -4 (3)

Use (3) minus for (2), we get:

4x - 5x -4y + 4y = -4 - 17

-x = -21

x = 21

4x - 4y = -4

84 - 4y = -4

-4y = -4 + 84

-4y = 80

y = 80 / -4

y = -20

d) 2x - 3y = 6

4x - 5y = 9 (1)

Multiply the first equation by 2, we got:

4x - 6y = 12 (2)

Use (1) minus for (2), we got:

4x -4x - 5y - 6y = 9 -12

-11y = -3

y = -3/-11

y = 3/11

2x - 3y = 6

2x - 9/11 = 6

2x = 66/11 + 9/ 11

2x = 75/11

x = 75/11 * 1/2

x = 75 / 22

e) x/2 + y/3 = 2

x/4 + y/3 = 4

Use the first equation subtract the second equation, we got:

x/2 - x/4 + y/3 - y/3 = 2 - 4

2x/4 -x/4 = -2

x/ 4 = -2

x = -2 * 4

x = -8

x/2 + y/3 = 2

-8 / 2 + y/3 = 2

y / 3 = 2 + 4

y/3 = 6

y = 6*3

y = 18

f) x/3 + y/2 = 3/2 (1)

x/2 + y/5 = -1/2 (2)

I don't know how to solve this, sr

Hope this helped :3

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ohaa [14]

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Answer:

scale factor: 3
rule: (x, y) ⇒ (3x +15, 3y -24)
center: (-7.5, 12)

Step-by-step explanation:

The scale factor can be found by comparing the length of CB to the length of RQ.

B-C = (-2, 8) -(-4, 9) = (2, -1)

Q-R = (9, 0) -(3, 3) = (6, -3)

The length of RQ is clearly 3 times the length of CB, so the scale factor (k) is ...

ratio of corresponding differences = 6/2 = -3/-1 = 3 . . . . . scale factor

We know that for dilation about a point O, the distance from O is multiplied by the scale factor. For dilation of point B to point Q, this means ...

k(B -O) = (Q -O)

Solving for Q, we get ...

Q = kB -kO +O . . . . this is what our dilation rule will look like.

The quantity O-kO can be found by subtracting kB:

Q -kB = O -kO = O(1 -k)

This is what we need for our dilation rule.

Q -kB = (9, 0) -3(-2, 8) = (9+6, 0-24) = (15, -24)

So, our dilation rule is ...

(x, y) ⇒ k(x, y) +(15, -24)

(x, y) ⇒ (3x +15, 3y -24) . . . . . dilation rule

The center of dilation can be found from ...

(Q -kB)/(1 -k) = O

O = (15, -24)/(1 -3) = (-7.5, 12)

The center of dilation is (-7.5, 12).

_____

<em>Additional comments</em>

On the graph, the center of dilation can be found by drawing a line through a point and its image. (Points are always dilated along a line through the center of dilation.) The intersection of two such lines is the center of dilation.

On this graph, the center is just above the top edge of the chart, at point (-7.5, 12). You can see this if you carefully draw lines BQ and AP.

You usually have coordinates for two original points and two image points, so finding the scale factor the way we did is not difficult. If you just have one point on the original and the image, the scale factor is found by finding their distances from the center of dilation. Each image point is k times as far as each original point from that center.

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The function of f(x) = 3x + 2 has a domain of -3 < x < 5. What is the domain of f-1(x)?

Flura [38]

<h3>Answer: -7 < x < 17</h3>

====================================================

Explanation:

Plug in the lower bound of the domain, which is x = -3

f(x) = 3x+2

f(-3) = 3(-3)+2

f(-3) = -9+2

f(-3) = -7

If x = -3, then the output is y = -7. Since f(x) is an increasing function (due to the positive slope), we know that y = -7 is the lower bound of the range.

If you plugged in x = 5, you should find that f(5) = 17 making this the upper bound of the range.

The range of f(x) is -7 < y < 17

Recall that the domain and range swap places when going from the original function f(x) to the inverse $f^{-1}(x)$

This swap happens because how x and y change places when determining the inverse itself. In other words, you go from y = 3x+2 to x = 3y+2. Solving for y gets us y = (x-2)/3 which is the inverse.

-----------------------

In short, we found the range of f(x) is -7 < y < 17.

That means the domain of the inverse is -7 < x < 17 since the domain and range swap roles when going from original to inverse.

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