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Cloud [144]
3 years ago
7

Brian drove 120 miles at speed of 60 miles per hour. He drove the same distance back home at average speed of 40 miles per hour.

What is his average speed?
Mathematics
1 answer:
IRINA_888 [86]3 years ago
4 0

Average speed = Total distance/Total time.

First drive:

120/60=2 (distance/rate=time)

Second drive:

120/40=3 (distance/rate=time)

Average:

Total time=120+120=240

Total time=3+2=5

Average speed = Total distance/Total time=240/5=48

His average speed was 48 mph.

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Meldie made a cube whose side is (3x - 2) inches. Find its volume in cubic inches.
irinina [24]

Answer:

x^2(3x-2) cubic inches OR in^3

OR

3x { 3 [ 3x ( x - 2 ) + 4 ] } - 8 cubic inches OR in^3

I AM UNAWARE IF YOU ASKED THAT ONE SIDE IS (3X-2) OR ALL. I WILL ANSWER BOTH PARTS

<em>-</em>

<em>NOTE</em><em>:</em><em> </em><em>'</em><em>^</em><em>'</em><em> </em><em>MEANS</em><em> </em><em>TO</em><em> </em><em>THE</em><em> </em><em>POWER</em><em> </em><em>OF</em><em>.</em><em>.</em>

<em>-</em>

Volume = v, abc = 3 sides of cube (height, width, length)

Using the formula for volume in a cube,

v = abc

We can solve this.

If one side is (3x-2)in,

  • (3x-2)(x)(x) = v.... x are the other two sides
  • x^2(3x-2) = v

x^2(3x-2) cubic inches OR in^3

If all sides are (3x-2)in,

Use the formula,

(a - b) ^{3}  =  {a}^{3}  + 3ab(b - a) -  {b}^{3}

We can solve this.

  • (3x-2)(3x-2)(3x-2) = v
  • (3x-2)^3 = v.... 3x = a and -2 = b
  • (3x)^3 + [(3)(3x)(2)][2-3x] - (2)^3 = v
  • 27x^3 + 18x(2-3x) -8 = v
  • (27x^3 + 36x - 54x^2) - 8 = v.. Terms inside brackets - take 3x as common and leave out 8
  • 3x(9x^2 -18x +12) = v... Take 3 as common again in the brackets
  • 3x [ 3 ([3x^2 -6x] + 4) -8 = v....Take 3x common in the terms in square brackets
  • 3x [ 3 [ 3x (x-2) + 4 ]] - 8 = v
  • 3x { 3 [ 3x ( x - 2 ) + 4 ] } - 8 = v

3x { 3 [ 3x ( x - 2 ) + 4 ] } - 8 cubic inches OR in^3

___

If you have any questions regarding formulas or anything, comment and I will get back to you asap.

___

5 0
1 year ago
You buy a 65 inch LED tv with an aspect ratio of 4:3. Find the width and height of the tv.
Bogdan [553]
3^2 +  4^2  = 5^2
65/5=13
3x13  =39
4 x 13= 42
3 0
2 years ago
Write the interval (5,100] as an inequality and using set notation
drek231 [11]

Answer: { x | 5 < x ≤ 100 }  OR  { x ∈ ℝ | 5 < x ≤ 100 }

Step-by-step explanation:

{ x | 5 < x ≤ 100 }

This means:

"The set of all x's, such that x is greater than 5 and less than or equal to 100"

Another acceptable way to write this is

{ x ∈ ℝ | 5 < x ≤ 100 }

"x ∈ ℝ" simply means x is an element of all real numbers

7 0
3 years ago
Type the correct answer in the box. express your answer to two significant figures. a reaction between 1.7 moles of zinc iodide
irga5000 [103]

The percent yield of zinc carbonate is 5.91%.

<h3>What is chemical reaction?</h3>

The chemical reaction is the reaction between two reactants which led to the formation of products.

The products are substances which forms after reaction. The reactants are the substances which are original materials.

Given is a reaction between 1.7 moles of zinc iodide and excess sodium carbonate yields 12.6 grams of zinc carbonate.

The given balanced equation is:  Na₂CO₃ + ZnI₂ → 2NaI + ZnCO₃

From given moles of zinc iodide, the moles of zinc carbonate

1.7 moles of ZnI₂ = 1.7 moles of ZnCO₃

Molar mass of zinc carbonate is 125.38 g/mol

Theoretical yield =  1.7 moles of ZnCO₃ x  125.38 g/mol = 213.15 g  ZnCO₃

Theoretical yield is 213.15 g and the actual yield is given as 12.6 g.

percent yield = [ 12.6 g / 213.15 g  ZnCO₃ ] x 100

percent yield = 5.91%

The percent yield of zinc carbonate is 5.91%.

Learn more about chemical reaction.

brainly.com/question/22817140

#SPJ1

7 0
2 years ago
Last week, labron jogged for 2 1/4 miles. This week , he plants to jog 2 times as far as last week. How many miles does Lebron P
Shtirlitz [24]

Answer:

4.5 miles

Step-by-step explanation:

2 times as far as last week

last week was 2.25 miles

2* 2.25 = 4.5 miles

7 0
3 years ago
Read 2 more answers
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