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2 years ago

Solve this simultaneous equation 4x+3y=18 x-3y=7

Mathematics

2 answers:

lys-0071 [83]2 years ago

7 0

Answer:

x=5, y = -2/3

Step-by-step explanation:

4x+3y=18

x-3y=7

Add the two equations together

4x+3y=18

x-3y=7

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

5x = 25

Divide by 5

5x/5 = 25/5

x = 5

Now solve for y

x - 3y = 7

5 -3y = 7

Subtract 5 from each side

5-3y-5 = 7-5

-3y = 2

Divide by -3

-3y/-3 = 2/-3

y = -2/3

sergeinik [125]2 years ago

4 0

Answer:

x = 5, y = -2/3

Step-by-step explanation:

4x+3y=18 .......make x the subject

4x = 18 - 3y

x = (18 - 3y )/4 ......equation 1

x-3y=7 ......make x the subject, follow the same method

x = 7 + 3y ......equation 2

then solve them ( equation1 and equation2 ) simultaneously:

7 + 3y = (18 - 3y )/4

( 7 + 3y ) * 4 = 18 - 3y

28 + 12y = 18 - 3y ........bring y in one side and numbers in another side

10 = - 15 y

y = - 2/3

if y = -2/3

then x = 7 + 3 ( -2/3 ) .....from equation 2

x = 7 - 2

x = 5

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What is the radius of a sphere if its surface area is 2,122.64 square inches? (Use 3.14 for π.) 11 in. 13 in. 121 in. 169 in.

crimeas [40]

To solve this, we are going to use the surface are of a sphere formula: $A=4 \pi r^2$
where
$A$ is the surface area of the sphere
$r$ is the radius of the sphere

We know for our problem that $A=2122.64$ and $\pi =3.14$ , so lets replace those vales in our formula:
$A=4 \pi r^2$
$2122.64=4(3.14)r^2$
$2122.64=12.56r^2$
Now, we just need to solve our equation for $r$ :
$\frac{2122.64}{12.56} =r^2$
$r^2=\frac{2122.64}{12.56}$
$r^2=169$
$r=+or- \sqrt{169}$
$r=13$ or $r=13$
Since the radius of a sphere cannot be a negative number, $r=13$ .

We can conclude that the radius of a sphere with surface area 2,122.64 $in^2$ is 13 in.

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3 years ago

The Great Pyramid has a height (h) of about 480 ft, a slant height (l) of about 560 ft and a square base of 756 ft. What is the

suter [353]

Answer: 91,445,760 ft³

Step-by-step explanation:

You know that the base of this pyramid is a square, then you can use the following formula to calculate its volume:

$V=\frac{s^2h}{3}$