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marissa [1.9K]
3 years ago
9

A2+2a-3=0 solving equations by completing the square

Mathematics
1 answer:
Olenka [21]3 years ago
8 0
I assume that you mean a^2 + 2a - 3 = 0

You need to find two numbers that multiply together to give the number 3 and when added give the answer 2 (as in 2a).  In this case the numbers are 3 and 1 (3 x 1 = 3 and 3 - 1 = 2)

Therefore we have
(a + 3)(a - 1) = 0

The values of x which solve the equation are -3 and 1
The reason is that -3 + 3 = 0 and 1 - 1 = 0 : zero times any number is zero


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Ad libitum [116K]
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Exponential since it increases by a multiplicative rate. It’s not constant
8 0
2 years ago
You spend $20 total on tubes of paint and disposable brushes for an art project. Tubes of paint cost $4.00 each and paintbrushes
hram777 [196]
You are buying 2 items so let's use two different variables to represent each:
p = number of tubes of paint
b = number of disposable brushes
cost = price per item × number of items
Equations from information given:
4p + 0.50b = 20 ← from the first 2 sentences
2p = b  ← if there are twice as many brushes as paint tubes you need 2 times paint tubes to equal number of brushes
Solve the problem by using substitution... 1b equals 2p so replace b with that:
4p + 0.50(2p) = 20
4p + 1p = 20   ← 0.50 is half so half of 2p is 1p
5p = 20 ← combine like terms
p = 4   ← divide both sides of the equation by 5
Recall the equation 2p = b replace p with 4
2(4) = b 
8 = b
ANSWER:
You purchased 4 tubes of paint and 8 disposable brushes.
8 0
2 years ago
Hi, I need some help with the last question of the first problem and the answer to the second page.
bulgar [2K]

Answer:

46.9 for the first one

Step-by-step explanation:

So sorry if i'm wrong <3

6 0
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If an architect wants to draw a plan for a house that is 75 ft by 80 ft, and his paper is 10 in. by 17 in., what is the best sca
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2 years ago
Drag each tile to the correct box. Vector t, with a magnitude of 4 meters/second and a direction angle of 60°, represents a swim
astraxan [27]

Answer:

From top to bottom, the boxes shown are number 3, 5, 6, 2, 4, 1 when put in ascending order.

Step-by-step explanation:

It is convenient to let a calculator or spreadsheet tell you the magnitude of the sum. For a problem such as this, it is even more convenient to let the calculator give you all the answers at once.

The TI-84 image shows the calculation for a list of vectors being added to 4∠60°. The magnitudes of the sums (rounded to 2 decimal places—enough accuracy to put them in order) are ...

... ║4∠60° + 3∠120°║≈6.08

... ║4∠60° + 4.5∠135°║≈6.75

... ║4∠60° + 4∠45°║≈7.93

... ║4∠60° + 6∠210°║≈3.23

... ║4∠60° + 5∠330°║≈6.40

... ║4∠60° + 7∠240°║≈ 3

_____

In the calculator working, the variable D has the value π/180. It converts degrees to radians so the calculation will work properly. The abs( ) function gives the magnitude of a complex number.

On this calculator, it is convenient to treat vectors as complex numbers. Other calculators can deal with vectors directly

_____

<em>Doing it by hand</em>

Perhaps the most straigtforward way to add vectors is to convert them to a representation in rectangular coordinates. For some magnitude M and angle A, the rectangular coordinates are (M·cos(A), M·sin(A)). For this problem, you would convert each of the vectors in the boxes to rectangular coordinates, and add the rectangular coordinates of vector t.

For example, the first vector would be ...

3∠120° ⇒(3·cos(120°), 3·sin(120°)) ≈ (-1.500, 2.598)

Adding this to 4∠60° ⇒ (4·cos(60°), 4°sin(60°)) ≈ (2.000, 3.464) gives

... 3∠120° + 4∠60° ≈ (0.5, 6.062)

The magnitude of this is given by the Pythagorean theorem:

... M = √(0.5² +6.062²) ≈ 6.08

___

<em>Using the law of cosines</em>

The law of cosines can also be used to find the magnitude of the sum. When using this method, it is often helpful to draw a diagram to help you find the angle between the vectors.

When 3∠120° is added to the end of 4∠60°, the angle between them is 120°. Then the law of cosines tells you the magnitude of the sum is ...

... M² = 4² + 3² -2·4·3·cos(120°) = 25-24·cos(120°) = 37

... M = √37 ≈ 6.08 . . . . as in the other calculations.

4 0
2 years ago
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