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ser-zykov [4K]
4 years ago
12

Which two equations would be most appropriately solved by using the quadratic formula?

Mathematics
1 answer:
leva [86]4 years ago
4 0

For this case we have that by definition, the quadratic formula is:x = \frac {-b \pm \sqrt {b ^ 2-4 (a) (c)}} {2a}

A quadratic equation is of the form:

ax ^ 2 + bx + c = 0

Option A: This equation can be solved without the quadratic formula

x ^ 2 = \frac {9} {3}\\x ^ 2 = 3\\x = \pm \sqrt {3}

Option B:

This equation is not as easy to solve by factoring or as option A. We can use the quadratic formula.

Option C:

-2x ^ 2 + 5x = 7

Similarly, this equation can be solved with the quadratic formula

Option D:

- (x - 3) (x + 9) = 0

In this factored equation we can see that the roots are

x_ {1} = 3\\x_ {2} = - 9

Answer:

Option B, C

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Khianna is trying to help her neighbor Mrs. Johnson design and estimate the cost of a new square patio to be made from 16 inch s
Gnoma [55]

Part I: Scale Drawing

<span>Decide on a scale factor to represent the distance covered by the patio. Then, use the space below to design Mrs. Johnson’s patio to be a square that is at least 8 feet on each side.</span>

 a) Scale Factor: 1 in/ 2 ft 

Use a straightedge and a ruler to draw to scale a design for Mrs. Johnson’s patio

b) see the picture attached

Mrs. Johnson’s patio to be a square that is 10 ft x 10 ft

<span><span>c) What are the dimensions of Mrs. Johnson’s patio? </span>
</span>the dimensions of Mrs. Johnson’s patio are 10 ft x 10 ft

<span><span>d) Calculate the area of Mrs. Johnson’s patio.  Show all work.  
</span> </span>
area of the square=b²
where b is the length side of the square
b=10 ft
so
Area=10²-----> area =100 ft²

<span><span>e) How many pavers will be needed?  Show all work. </span>
</span>
we know that
1 paver is 16 in x 16 in dimensions
convert to ft
1 ft----------->12 in
x ft-----------> 16 in
x=16/12-----> x=4/3 ft
so
1 paver is (4/3) ft x (4/3) ft dimensions

area of one paver=(4/3)²----> 16/9 ft²

if one paver has an area of----------------> 16/9 ft²
x pavers----------------------->  100 ft²
x=100/(16/9)------> x=100*9/16-----> x=56.25 pavers

if one box --------------> 12 pavers
x box---------> 56.25 pavers
x=56.25/12-----> x=4.68 box-------> x=5 boxes
5 boxes of pavers will be needed 

<span><span>f) What will it cost to build the patio?  Show all work. 
 </span> </span>
the cost of one box is--------> $99.99
5 boxes-----------> x
x=5*$99.99------>x=$499.95

the cost to build the patio is $499.95

Part II: Bigger Design

<span>There is a saying that bigger is better, so why not double the dimensions of Mrs. Johnson’s patio to make the side measurement twice as big? Mrs. Johnson and I think that it would better meet her needs.  After seeing the original estimation, she thinks that she could afford to double the size. I explained that making the patio twice as big would mean twice the cost. Mrs. Johnson says, “Let’s do it!”</span>

 

<span>a) What would be the new dimensions of Mrs. Johnson’s patio?
</span>the new  dimensions of Mrs. Johnson’s patio are 20 ft x 20 ft

<span>b) Calculate the new area of Mrs. Johnson’s patio.  Show all work.
</span>area of the square=b²
where b is the length side of the square
b=20 ft
so 
Area=20²-----> area =400 ft²<span>  
</span>
<span><span>c) How many pavers will be needed for the new design?  Show all work.
</span> </span>
1 paver is (4/3) ft x (4/3) ft dimensions

area of one paver=(4/3)²----> 16/9 ft²

if one paver has an area of----------------> 16/9 ft²
x pavers----------------------->  400 ft²
x=400/(16/9)------> x=400*9/16-----> x=225 pavers

if one box --------------> 12 pavers
x box---------> 225 pavers
x=225/12-----> x=18.75 box-------> x=19 boxes
19 boxes of pavers will be needed 

<span>d) What will it cost to build the bigger patio?  Show all work. 
</span>the cost of one box is--------> $99.99
19 boxes-----------> x
x=19*$99.99------>x=$1899.81
the cost to build the bigger patio is $1899.81

<span><span>e) Is Khianna right?  Will doubling the size of the patio, double the cost?</span>
</span>
<span>Khianna is wrong to double the dimensions the cost quadruples</span>

5 0
4 years ago
If a=mg-kv2/m,find,correct to the nearest whole number the value of v when a=2.8,m=12,g=9.8 and k=8/3
Cerrena [4.2K]

Answer:

v = 23

Step-by-step explanation:

Formatting the question gives;

a = mg - kv² / m

Make v subject of the formula as follows;

(i) Multiply both sides by m

ma = m²g - kv²

(ii) Collect like terms

kv² = m²g - ma

(iii) Divide through by k

v² = (m²g - ma) / k

(iv) Take the square root of both sides

v = √ [(m²g - ma) / k]            --------------(ii)

From the question:

a = 2.8

m = 12

g = 9.8

k = 8/3

Substitute these values into equation (i) as follows;

v = √ [(12²(9.8) - 12(2.8)) / (8/3)]

v = √ [(1411.2 - 33.6) / (8/3)]

v = √ [1377.6 / (8/3)]

v = √ [1377.6 x (3/8)]

v = √ [1377.6 x 3 / 8)]

v = √ [516.6]

v = 22.73

v = 23 [to the nearest whole number]

Therefore v = 23 to the nearest whole number    

3 0
4 years ago
What number is halfway between 60and 70
tatuchka [14]

Answer:

65

Step-by-step explanation:

70 - 60 = 10

10 / 2 = 5

Thus 65

5 0
4 years ago
Read 2 more answers
Frank wants to buy three items costing $111.32, $28.75, and $73.21. If he earns $8.75 an hour, how many hours must Frank work be
Sedaia [141]

The three items cost altogether is : 111.32 + 28.75 + 73.21 = 213.28

So, he must work 213.28 : 8.75 = 24.3748571429...

Since if he works 24 hours, he wouldn't have enough money to buy the 3 items, so he must work 24 + 1 = 25 hours.

Recheck : 25 x 8.75 = 218.75 ( > 213.28)

4 0
3 years ago
68.6943 rounded to tbe nearest tenth
lutik1710 [3]

The answer to this is 68.7

The tenths place is the first term right after the decimal point. We see a "6" there. Look the number right after that. There is a "9". Since 9 is greater than 5, we round up the "6" to "7".

3 0
3 years ago
Read 2 more answers
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