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Neko [114]
3 years ago
7

If a^2+1/a^2=79 where (a>0), find the value of a^3 +1/a^3

Mathematics
1 answer:
Nastasia [14]3 years ago
7 0

Note the binomial expansion,

(<em>a</em> + 1/<em>a</em>)³ = <em>a</em> ³ + 3<em>a</em> + 3/<em>a</em> + 1/<em>a</em> ³

so

<em>a</em> ³ + 1/<em>a</em> ³ = (<em>a</em> + 1/<em>a</em>)³ - 3 (<em>a</em> + 1/<em>a</em>)

Similarly,

(<em>a</em> + 1/<em>a</em>)² = <em>a</em> ² + 2 + 1/<em>a</em> ²

We're given <em>a</em> ² + 1/<em>a</em> ² = 79, so

(<em>a</em> + 1/<em>a</em>)² - 2 = 79

(<em>a</em> + 1/<em>a</em>)² = 81

<em>a</em> + 1/<em>a</em> = ±9

but <em>a</em> > 0, so we ignore the negative solution.

Then

<em>a</em> ³ + 1/<em>a</em> ³ = 9³ - 3×9 = 702

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Start by looking at the vertex form of a quadratic function, f(x) = a(x - h)^2 + k. The variables h and k are the values of the vertex. Plug those in to get f(x) = a(x - 4)^2 + 5. To find the variable a, plug in the point given for the x and y values. So, you get (21) = a((8) - 4)^2 + 5. Solve for a algebraically, and you get a = 1. Finally, plug everything in and simplify the equation. You should get that the quadratic function is f(x) = x^2 - 8x + 21. Hope this helps!

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3 years ago
Ashwin helps paint a square mural in his classroom. Then he helps paint a mural in the hallway whose length is 7 feet longer and
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Ashwin paints 2 murals:

  1. A square mural in his classroom
  2. A mural in the hallway with length 7 feet longer and width 3 feet shorter

Also, x indicates the side length of the mural in the classroom. Since the classroom mural is square in shape, the length and breadth of the mural would be x.

Part A: Expression to represents the two binomials to be multiplied to find the area of the hallway mural

Area of the hallway mural = Length of the hallway mural × Breadth of the hallway mural

So Length of the hallway mural = Length of the classroom mural + 7

⇒ Length of the hallway mural = x + 7

Breadth of the hallway mural = Breadth of the classroom mural - 3

⇒ Breadth of the hallway mural = x - 3

Hence, x + 7 and x - 3 need to be multiplied to determine the area of the mural

Part B: Area of the hallway mural

Area of the hallway mural = Length of the hallway mural × Breadth of the hallway mural

⇒ Area of the hallway mural = (x + 7) × (x-3)

⇒ Area of the hallway mural = x² + 7x - 3x - 21

⇒ Area of the hallway mural = x² + 4x - 21

Part C: Area of the hallway mural if each side of the classroom mural is 8 foot long

Putting the value x = 8 in the answer of Part B

⇒ Area of the hallway mural = 8² + 4×8 - 21

⇒ Area of the hallway mural = 64 + 4×8 - 21

⇒ Area of the hallway mural = 64 + 32 - 21

⇒ Area of the hallway mural = 75 square feet


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oakwood has a mass of 2.85 kilograms and a volume of 4100 cubic centimeters. determine the density of oak in grams per cubic cen
bogdanovich [222]

Answer:

The density of oak is <u>0.695</u> grams per cubic centimeter.

Step-by-step explanation:

Given:

Oakwood has a mass of 2.85 kilograms and a volume of 4100 cubic centimeters.

Now, to find the density of oak in grams per cubic centimeter.

Mass (m) = 2.85 kilograms.

So, using conversion factor we convert into grams:

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Volume (v) = 4100 cubic centimeters.

Now, to get the density by using formula:

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Therefore, the density of oak is 0.695 in grams per cubic centimeter.

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