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Nookie1986 [14]
3 years ago
6

Expand and simplify (2x+1)(x+3)

Mathematics
1 answer:
MissTica3 years ago
7 0

Answer:

2x^2+7x+3

Step-by-step explanation:

(2x+1)(x+3)

2xx+2(3x+1)(x+1)(3)

2x^2+7x+3

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Molly's Custom Kitchen Supplies sells handmade forks and spoons. It costs the store $1.70 to buy the
scoray [572]

9514 1404 393

Answer:

  • 7 forks
  • 20 spoons

Step-by-step explanation:

Let x and y represent the numbers of forks and spoons made, respectively.

The cost of materials is ...

  1.70x + 1.30y = 37.90

The revenue from sales is ...

  5.60x + 5.40y = 147.20

You can solve these by any of your favorite methods. A graph is attached. It shows the solution is (x, y) = (7, 20).

They made 7 forks and 20 spoons.

_____

<em>Additional working out</em>

The equation coefficients are not "nice" multiples of each other, so elimination  and substitution will require multiplying both equations by some numbers. If we're going to that trouble, we may as well use Cramer's Rule or a variation of the "cross multiplication method". The latter is relatively straightforward and can be easy to remember. It tells you the solution to ...

  ax +by +c = 0

  dx +ey +g = 0

is ...

  1/(ae-db) = x/(bg-ey) = y/(cd-ga)

Here, that becomes ...

  1/(1.70·5.40-5.60·1.30) = x/(1.30·(-147.20)-5.40·(-37.90))

  = y/(-37.90·5.60-(-147.20·1.70))

  1/1.9 = x/13.3 = y/38

  x = 13.3/1.9 = 7 . . . number of forks

  y = 38/1.9 = 20 . . . number of spoons

__

The above solution formula may be more easily remembered in terms of the cross-multiplication pattern that gives the method its name. When the coefficients are written in two rows of four, with the last being a repeat of the first:

  • a b c a
  • d e g d

each of the three denominators (of 1, x, and y) is the difference of products in adjacent columns, formed in an X fashion: ae-db, bg-ec, cd-ga. Note that the equations are written in "general" form, which is similar to "standard" form, but with all of the non-zero terms on the left of the equal sign. (This has the effect of changing the sign of the constants: 1.7x+1.3y=37.9 ⇒ 1.7x+1.3y-37.9=0)

8 0
3 years ago
In a right triangle ABC, CD is an altitude, such that AD=BC. Find AC, if AB=3 cm, and CD= 2 cm.
konstantin123 [22]

Consider right triangle ΔABC with legs AC and BC and hypotenuse AB. Draw the altitude CD.

1. Theorem: The length of each leg of a right triangle is the geometric mean of the length of the hypotenuse and the length of the segment of the hypotenuse adjacent to that leg.

According to this theorem,

BC^2=BD\cdot AB.

Let BC=x cm, then AD=BC=x cm and BD=AB-AD=3-x cm. Then

x^2=(3-x)\cdot 3,\\ \\x^2=9-3x,\\ \\x^2+3x-9=0,\\ \\D=3^2-4\cdot (-9)=9+36=45,\\ \\\sqrt{D}=\sqrt{45}=3\sqrt{5},\\ \\x_1=\dfrac{-3-3\sqrt{5} }{2}0.

Take positive value x. You get

AD=BC=\dfrac{-3+3\sqrt{5} }{2}\ cm.

2. According to the previous theorem,

AC^2=AD\cdot AB.

Then

AC^2=\dfrac{-3+3\sqrt{5} }{2}\cdot 3=\dfrac{-9+9\sqrt{5} }{2},\\ \\AC=\sqrt{\dfrac{-9+9\sqrt{5} }{2}}\ cm.

Answer: AC=\sqrt{\dfrac{-9+9\sqrt{5} }{2}}\ cm.

This solution doesn't need CD=2 cm. Note that if AB=3cm and CD=2cm, then

CD^2=AD\cdot DB,\\ \\2^2=AD\cdot (3-AD),\\ \\AD^2-3AD+4=0,\\ \\D

This means that you cannot find solutions of this equation. Then CD≠2 cm.

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3 years ago
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sergiy2304 [10]

The answer is 12!

Hope this helps! :D

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4 0
3 years ago
"Which ranges describe the cluster in the scatter plot?
Minchanka [31]
A.between 8 and 10 years of age,
<span>C.between 10 and 12 years of age

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7 0
3 years ago
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Triangle ABC has vertices A(–2, –3), B(–5, –3), and C(–4, –2). The triangle is rotated 90° counterclockwise around the origin.
Ulleksa [173]
The rule for this rotation is (x, y) converted into (-y, x). So, to find the answer you would make the y negative and switch the values in the ordered pair. A would be (3, -2), B would be (3, -5), and C would be (2, -4). So, your answer would be B. Hope this helps!
4 0
3 years ago
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