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Zina [86]
3 years ago
5

Explain when to use Mental Math

Mathematics
1 answer:
I am Lyosha [343]3 years ago
3 0
It is best to use mental math with some equations (5x5 or something that is easy enough that work does not have to be shown 10 dived by 5
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A rectangular parcel of land has an area of 6,000 ft2. A diagonal between opposite corners is measured to be 10 ft longer than o
Drupady [299]

Answer:

50ft by 120ft

Step-by-step explanation:

Area of a rectangle = L × W

6000ft² = L × W

L = 6000/W

When a diagonal line divides a rectangle into 2 right angled triangles, the diagonal line = Hypotenuse of either of the triangle and it is the longest side.

The formula for a right angle triangle =

a² + b² = c²( c = hypotenuse)

We are told in the question that:

A diagonal between opposite corners is measured to be 10 ft longer than one side of the parcel

Let us assume the side that the hypotenuse is longer than = Width

Hence, the Diagonal = (W + 10)²

Therefore

L² + W² = (W + 10)²

Since L = 6000/W

W² + (6000/W)² = (W + 10)²

W² + (6000/W)² = (W + 10) (W + 10)

W² + (6000/W)² = W² + 10W + 10W + 100

W² + (6000/W)² = W² + 20W + 100

W² - W² + (6000/W)² = 20W+ 100

6000²/W² = 20W + 100

6000² = W²( 20W + 100)

6000² = 20W³ + 100W²

20W³ + 100W² - 6000² = 0

20W³ + 100W² - 36000000 = 0

20(W³ + 5W² - 1800000) = 0

Factorising the quadratic equation,

20(W − 120)(W² + 125W + 15000) = 0

W - 120 = 0

W = 120

Therefore,

W(Width) = 120feet

Since the Width = 120 feet

We can find the length

6000ft² = L × W

L = 6000/W

L = 6000/120

L = 50 feet

The dimensions of the land, correct to the nearest foot is 50ft by 120ft

3 0
3 years ago
Simplify the expression (9 + 2i)(9 − 2i).<br><br> 81 − 18i<br> 81 + 18i<br> 77<br> 85
Ymorist [56]

Answer:

=85

Step-by-step explanation:

I'm pretty sure I'm correct

5 0
3 years ago
Solve the equation of 2x=64
Elina [12.6K]

2x = 64

Divide both sides by 2:

X = 64/2

X = 32

8 0
3 years ago
Read 2 more answers
In need of help of these math questions
vitfil [10]

Answer:

1. 4

2.  6.4

3. 10.0828313253

Explanation:

2.

15/12=1.25

8/1.25=6.4

3. ill write explanation for 3 later im  occupied those are the correct answers

problably they want you to round to nearest tenth

4 0
3 years ago
I think of a number add 1 then double the results help for my mate
zalisa [80]
18 what is this for exactly..?
5 0
4 years ago
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