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2 years ago

Find the value of two numbers if their sum is 21 and their difference is 5

Mathematics

1 answer:

kykrilka [37]2 years ago

6 0

Answer: x = 13 and y = 8

Step-by-step explanation:

Two numbers must add to 21. We don't know them yet, so let's just use a placeholder for both of them for now.

x + y = 21

Their difference is five, meaning that if we subtract one from the other, we get five. Again, we don't know the numbers yet, so we'll add a placeholder for now.

x - y = 5

We can now solve a system of equations for x.

x = y + 5

y + 5 + y = 21

2y + 5 = 21

2y = 16

y = 8

x - 8 = 5

x = 13

So x = 13 and y = 8

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Find an equation of the line containing the centers of the two circles whose equations are given below.

Anna35 [415]

Answer:

Step-by-step explanation:

The general equation of a circle is expressed as x²+y²+2gx+2fy+c = 0 with centre at C (-g, -f).

Given the equation of the circles x²+y²−2x+4y+1 =0 and x²+y²+4x+2y+4 =0, to get the centre of both circles,<em> we will compare both equations with the general form of the equation above as shown;</em>

For the circle with equation x²+y²−2x+4y+1 =0:

2gx = -2x

2g = -2

Divide both sides by 2:

2g/2 = -2/2

g = -1

Also, 2fy = 4y

2f = 4

f = 2

The centre of the circle is (-(-1), -2) = (1, -2)

For the circle with equation x²+y²+4x+2y+4 =0:

2gx = 4x

2g = 4

Divide both sides by 2:

2g/2 = 4/2

g = 2

Also, 2fy = 2y

2f = 2

f = 1

The centre of the circle is (-2, -1)

Next is to find the equation of a line containing the two centres (1, -2) and (-2.-1).

The standard equation of a line is expressed as y = mx+c where;

m is the slope

c is the intercept

Slope m = Δy/Δx = y₂-y₁/x₂-x₁

from both centres, x₁= 1, y₁= -2, x₂ = -2 and y₂ = -1

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

m = -1+2/-3

m = -1/3

The slope of the line is -1/3

To get the intercept c, we will substitute any of the points and the slope into the equation of the line above.

Substituting the point (-2, -1) and slope of -1/3 into the equation y = mx+c

-1 = -1/3(-2)+c

-1 = 2/3+c

c = -1-2/3

c = -5/3

Finally, we will substitute m = -1/3 and c = 05/3 into the equation y = mx+c.

y = -1/3 x + (-5/3)

y = -x/3-5/3

Multiply through by 3

3y = -x-5

3y+x = -5

<em>Hence the equation of the line containing the centers of the two circles is 3y+x = -5</em>

5 0

2 years ago

All the fourth-graders in a certain elementary school took a standardized test. A total of 85% of the students were found to be

Aneli [31]

Answer:

There is a 2% probability that the student is proficient in neither reading nor mathematics.

Step-by-step explanation:

We solve this problem building the Venn's diagram of these probabilities.

I am going to say that:

A is the probability that a student is proficient in reading

B is the probability that a student is proficient in mathematics.

C is the probability that a student is proficient in neither reading nor mathematics.

We have that:

$A = a + (A \cap B)$

In which a is the probability that a student is proficient in reading but not mathematics and $A \cap B$ is the probability that a student is proficient in both reading and mathematics.

By the same logic, we have that:

$B = b + (A \cap B)$

Either a student in proficient in at least one of reading or mathematics, or a student is proficient in neither of those. The sum of the probabilities of these events is decimal 1. So

$(A \cup B) + C = 1$

In which

$(A \cup B) = a + b + (A \cap B)$

65% were found to be proficient in both reading and mathematics.

This means that $A \cap B = 0.65$

78% were found to be proficient in mathematics

This means that $B = 0.78$

$B = b + (A \cap B)$

$0.78 = b + 0.65$

$b = 0.13$

85% of the students were found to be proficient in reading

This means that $A = 0.85$

$A = a + (A \cap B)$

$0.85 = a + 0.65$

$a = 0.20$

Proficient in at least one:

$(A \cup B) = a + b + (A \cap B) = 0.20 + 0.13 + 0.65 = 0.98$

What is the probability that the student is proficient in neither reading nor mathematics?

$(A \cup B) + C = 1$

$C = 1 - (A \cup B) = 1 - 0.98 = 0.02$

There is a 2% probability that the student is proficient in neither reading nor mathematics.

6 0

2 years ago

What the slope (0,-1) and (2,-5)

34kurt

Answer:

-4/2, or finding slope is (difference of y)/(difference of x) inserting those numbers into the equation would be (-5-(-1))/(2-0), which would become -4/2, which is basically -2.

3 0

2 years ago

Read 2 more answers

a group of 50 people were asked their gender and if they liked cats. the data from the survey are shown in the ben diagram. dete

sasho [114]

Answer:

A=13, b= 28, c= 6 d=22 e=31

Step-by-step explanation:

E = 15 +16 = 31

6 males like cats ( the middle section) so C = 6

d = 6 +16 = 22

a = 19-6 = 13

b = 50-22 = 28

so in order: a = 13, b = 28, c = 6, d = 22, e = 31

6 0

2 years ago

Kiersten runs a website that helps people learn to programme. Every month, Kiersten receives a subscription fee of a 10 from eac

blondinia [14]

1,200?? I'm not really sure tho

6 0

2 years ago