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3 years ago

Help please! Note: Use ELIMINATION!!!

Mathematics

2 answers:

Verdich [7]3 years ago

7 0

Multiplying the second equation by 4/3 and adding it to the first, we get 36=9x and by dividing both sides by 9, we get x=4. Next, we can plug that into the second equation (it doesn't matter which equation) to get 3*4-3y=18=12-3y. Subtracting 12 from both sides, we get 6=-3y and by dividing both sides by -3 we get y=-2

Ymorist [56]3 years ago

4 0

The answers are 24 and -2

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Answer:

a) h = 123/x^2

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Step-by-step explanation:

a) The volume is given by ...

V = Bh

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b) The surface area is the sum of the area of the base (x^2) and the lateral area, which is the product of the height and the perimeter of the base.

$S=x^2+Ph=x^2+(4x)\dfrac{123}{x^2}\\\\S=x^2+\dfrac{492}{x}$

c) The derivative of the area with respect to x is ...

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$0=2x -\dfrac{492}{x^2}\\\\0=x^3-246\\\\x=\sqrt[3]{246}\approx 6.26583$

d) The second derivative is ...

$S''=2+\dfrac{2\cdot 492}{x^3}=2+\dfrac{2\cdot 492}{246}=6$

This is positive, so the value of x found represents a minimum of the area function.

e) The minimum area is ...

$S=x^2+\dfrac{2\cdot 246}{x}=(246^{\frac{1}{3}})^2+2\dfrac{246}{246^{\frac{1}{3}}}=3\cdot 246^{\frac{2}{3}}\approx 117.78$

The minimum area of metal used is about 117.78 m².

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According to the data in the figure, find the value of x and y.

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