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Flauer [41]
3 years ago
7

Find an equation of the tangent line to the curve 2(x^2+y^2)2=25(x^2−y^2) (a lemniscate) at the point (3,1)

Mathematics
1 answer:
Sholpan [36]3 years ago
6 0
\bf 2[x^2+y^2]^2=25(x^2-y^2)\qquad \qquad 
\begin{array}{lllll}
&x_1&y_1\\
%   (a,b)
&({{ 3}}\quad ,&{{ 1}})\quad 
\end{array}\\\\
-----------------------------\\\\
2\left[ x^4+2x^2y^2+y^4 \right]=25(x^2-y^2)\qquad thus
\\\\\\
2\left[ 4x^3+2\left[ 2xy^2+x^22y\frac{dy}{dx} \right]+4y^3\frac{dy}{dx} \right]=25\left[2x-2y\frac{dy}{dx}  \right]
\\\\\\
2\left[ 4x^3+2\left[ 2xy^2+x^22y\frac{dy}{dx} \right]+4y^3\frac{dy}{dx} \right]=50\left[x-y\frac{dy}{dx}  \right]
\\\\\\


\bf \left[ 4x^3+2\left[ 2xy^2+x^22y\frac{dy}{dx} \right]+4y^3\frac{dy}{dx} \right]=25\left[x-y\frac{dy}{dx}  \right]
\\\\\\
4x^3+4xy^2+4x^2y\frac{dy}{dx}+4y^3\frac{dy}{dx}+25y\frac{dy}{dx}=25x
\\\\\\
\cfrac{dy}{dx}[4x^2y+4y^3+25y]=25x-4x^3+4xy^2
\\\\\\
\cfrac{dy}{dx}=\cfrac{25x-4x^3+4xy^2}{4x^2y+4y^3+25y}\impliedby m=slope

notice... a derivative is just the function for the slope

now, you're given the point 3,1, namely x = 3 and y = 1

to find the "m" or slope, use that derivative, namely f'(3,1)=\cfrac{25x-4x^3+4xy^2}{4x^2y+4y^3+25y}

that'd give you a value for the slope

to get the tangent line at that point, simply plug in the provided values
in the point-slope form

\bf y-{{ y_1}}={{ m}}(x-{{ x_1}})\qquad
\begin{cases}
x_1=3\\
y_1=1\\
m=slope
\end{cases}\\ \qquad \uparrow\\
\textit{point-slope form}

and then you solve it for "y", I gather you don't have to, but that'd be the equation of the tangent line at 3,1

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a rhombus as an area of 72 ft and the product of the diagonals is 144. What is the length of each diagonal?
SashulF [63]

A = (1/2)(x)(y)

Let x = diagonal 1

Let y = diagonal 2

The product of xy = 144.

This means that x = 12 and y = 12.

So, 12 • 12 = 144

Each diagonal is 12 feet.

Prove:

72 feet = (1/2)(12)(12) feet

72 feet = (1/2)(144) feet

72 feet = 72 feet

6 0
3 years ago
Can anyone help pls two more
Andreas93 [3]

Answer:

I'll explain below, just follow the directions. I can't directly draw it.

Step-by-step explanation:

find the length and the width of a rectangle whose perimeter is 18 ft

2L + 2W = 18

simplify, divide by 2

L + W = 9

L = (9-W)

:

whose area is 20 square feet

L*W = 20

Replace L with (9-W)

 

W(9-W) = 20

-W^2 + 9W - 20 = 0

Multiply by -1, easier to factor

W^2 - 9W + 20

Factors to

(W-4)(W-5) = 0

Two solutions

W = 4 ft is width, then 5 ft is the Length

and

W = 5 ft is the width, then 4 ft

5 0
3 years ago
Round 18.57631 to three decimal places.
iVinArrow [24]

❄ Hi there,

let us revise the rounding rules and then, get down to rounding the number.

\sf{Rounding \ Rules:}

  • If the number you need to round is followed by a number from 0 to 4, you round down.
  • If the number you need to round is followed by a number that's 5 or more, you round up.

Now we can start the rounding process.

Reading the problem & the directions, we notice that we need to round to 3 decimal places (3 numbers after the decimal point).

Looking at the fourth number, we notice that it's less than 5.

∴ we need to round down ↡

↬\sf{18.57631 \ rounded \ to \ 3 \ DP \ = \bf{18.576}}

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

❄

3 0
2 years ago
I have no clue how to do any of these problems so if anyone knows any an explanation would be nice.
Sever21 [200]
#1).  The length of the whole circumference is (π · D) = 12π .

         120° is 1/3 of 360°, so arc-AB is 1/3 of the whole circumference.

#2).  60° is 1/6 of 360°.
         So arc-CD is 1/6 of the whole circumference (which is given).

#3).  The circumference of the circle is (π·D) = 20π .

         70° is (70°/360°) of the whole circle, so arc-XY
         is  (70/360) of the whole circumference.

#4).  Sorry, I don't remember anything right now about
         angles between chords. 
         I hope what I've given you so far is worth 5 points.
7 0
3 years ago
What is the inverse of y = 3x + 9? A. y= 1/3x - 3 B. y = 1/3x + 9 C. y = -1/3x - 3 D. y = 9x + 3
Aneli [31]

Answer:

1/3x - 3

Step-by-step explanation:

To find the inverse, we exchange x and y and then solve for y

y =3x+9

Exchange x and y

x = 3y+9

Then solve for y

Subtract 9 from each side

x-9 =3y+9-9

x-9 = 3y

Divide by 3

1/3(x-9) = 3y/3

1/3(x-9) = y

Distribute

1/3x-3 = y

The inverse is 1/3 x -3

6 0
3 years ago
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