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makkiz [27]
3 years ago
12

The ratio of the surface area of two cubes is 49:81. Find the ratio of there volumes.​

Mathematics
2 answers:
Liono4ka [1.6K]3 years ago
7 0

Answer:

343 : 729

Step-by-step explanation:

A cube is made up of 6 square faces. If each face has a side length of a, we can find the surface area of that cube with the formula A=6a^2, since we'll have 6 faces with area a². Let's call the edge length of the first cube a and the edge length of the second cube b. The ratio between their surface areas is then 6a² : 6b², or simply a² : b². If we compare this to our given ratio 49 : 81, we can see that a² = 49 and b² = 81, or, square rooting both equations, a = 7 and b = 9.

The volume of a cube with a side length a is a³, so the ratio between our cubes here must be a³ : b³. Using the values for a and b we just found, this ratio becomes 7³ : 9³, which we can simplify to 343 : 729.

tia_tia [17]3 years ago
4 0

Answer:

343 : 729

Step-by-step explanation:

If the ratio of the sides of a cube = a : b , then

ratio of areas = a² : b² and

ratio of volumes = a³ : b³

Given ratio of areas = 49 : 81, then

ratio of sides = \sqrt{49} : \sqrt{81} = 7 : 9 , so

ratio of volumes = 7³ : 9³ = 343 : 729

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Answer:

x = 5

Step-by-step explanation:

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Please help on two math questions. I don’t understand how to do them.
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x\leq -2 \lor\ x>1

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(-\infty,-2]\cup (1,\infty)

In the second case, you are looking for all numbers between -3 and 5. This interval is symmetric with respect to 1: you're considering all numbers that are at most 4 units away from 1, both to the left and to the right.

This means that the difference between your numbers at 1 must be at most 4, which is modelled by

|x-1|\leq 4

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3 0
3 years ago
Yesterday,Bethany sent 60 text messages. she said 15 percent of those messages were to her best friend. How many texts messages
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9

Step-by-step explanation:

We have to multiply 60 by 15%

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7 0
3 years ago
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A tree that is 14 feet tall casts a shadow that is 30 feet long. Find the angle of the elevation from the top of the shadow to t
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iren2701 [21]
0.19 for one cookie and 0.59 for one doughnut

x for how much one cookie costs and y for how much one doughnut costs
6x+4y=3.5
12x+5y=5.23

solve by substitution: (elimination would work too)
4y=3.5-6x
y=0.875-1.5x
12x+5(0.875-1.5x)=5.23
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Check the work: 6(0.19)+4(0.59)=3.5
4 0
3 years ago
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