A smartphone costs $250. Sale tax is 6%. What is the total cost, including tax?

Use implicit differentiation to find the slope of the tangent line at the given point:

Salsk061 [2.6K]

Answer:

$\frac{dy}{dx}=0$

Step-by-step explanation:

So we have the equation:

$(x^2+y^2)^2=4x^2y$

And we want to find the slope of the tangent line at the point (1,1).

So, let's implicitly differentiate. Take the derivative of both sides:

$\frac{d}{dx}[(x^2+y^2)^2]=\frac{d}{dx}[4x^2y]$

Let's do each side individually.

Left:

We can use the chain rule:

$(u(v(x))'=u'(v(x))\cdot v'(x)$

Let's let v(x) be x²+y². So, u(x) is x². Thus, the u'(x) is 2x. Therefore:

$\frac{d}{dx}[(x^2+y^2)^2]=2(x^2+y^2)(\frac{d}{dx}[x^2+y^2])$

We can differentiate x like normal. However, for y, we must differentiate implicitly. pretend y is y(x). This gives us:

$\frac{d}{dx}[(x^2+y^2)^2]=2(x^2+y^2)(\frac{d}{dx}[x^2]+\frac{d}{dx}[y^2(x)])$

Differentiate:

$\frac{d}{dx}[(x^2+y^2)^2]=2(x^2+y^2)(2x+2y\frac{dy}{dx})$

Therefore, our left side is:

$2(x^2+y^2)(2x+2y\frac{dy}{dx})$

Right:

We have:

$\frac{d}{dx}[4x^2y]$

Let's move the 4 outside:

$=4\frac{d}{dx}[x^2y]$

Use the product rule:

$=4(\frac{d}{dx}[x^2]y+x^2\frac{d}{dx}[y])$

Differentiate:

$=4(2xy+x^2\frac{dy}{dx})$

Therefore, our entire equation is:

$2(x^2+y^2)(2x+2y\frac{dy}{dx})=4(2xy+x^2\frac{dy}{dx})$

So, to find the derivative at (1,1), substitute 1 for x and 1 for y.

$2((1)^2+(1)^2)(2(1)+2(1)\frac{dy}{dx})=4(2(1)(1)+(1)^2\frac{dy}{dx})$

Evaluate.

$2((1)+(1))(2+2\frac{dy}{dx})=4(2+\frac{dy}{dx})$

Simplify. Also, let's distribute the right:

$2(2)(2+2\frac{dy}{dx})=8+4\frac{dy}{dx}$

Multiply.

$4(2+2\frac{dy}{dx})=8+4\frac{dy}{dx}$

Distribute the left:

$8+8\frac{dy}{dx}=8+4\frac{dy}{dx}$

Subtract 8 from both sides:

$8\frac{dy}{dx}=4\frac{dy}{dx}$

Subtract 4(dy/dx) from both sides:

$4\frac{dy}{dx}=0$

Divide both sides by 4:

$\frac{dy}{dx}=0$

Therefore, the slope at the point (1,1) is 0.

And we're done!

We can verify this using the graph. The slope of the line tangent to the point (1,1) seems like it would be horizontal, giving us a slope of 0.

Edit: Typo

5 0

3 years ago

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FUNCION AFÍN O LINEAL. Una empresa de gas cobra el servicio del siguiente modo: un cargo fijo de $140, mas un importe por el con

antoniya [11.8K]

Answer:

El costo es:

Primero tenemos un cargo fijo de $140.

Luego tenemos un $25 por cada m^3 consumido.

Entonces, si tenemos x m^3 consumidos en un mes, el cargo de ese mes va a ser:

C(x) = $140 + $25*x.

Esto es una relación linear.

A) En este caso tendríamos x = 140

C(140) = $140 + $25*140 = $3640

B) La formula es, como ya escribimos arriba, C(x) = $140 + $25*x.

C) El grafico estará al final. En el podemos ver que la linea corta el eje vertical en y = $140, que seria lo minimo que se puede pagar al mes, en el caso de que el consumo sea x = 0.

D) La ordenada al origen es $140, representa el cargo fijo que no depende de la variable x.

5 0

4 years ago

What is 2/9 divided by 3/4?

harina [27]

2/9 divided by 3/4 is the same as 2/9 multiplied by 4/3, so write that as an equation:
2/9 x 4/3 =
8/27 is your answer.

4 0

3 years ago

Is 1234.... infinite or finite

nlexa [21]

Answer:

infinite set

Step-by-step explanation:

4 0

3 years ago

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Please help

DedPeter [7]

Answer:

Step-by-step explanation:

Given the expression $\sqrt{10} * \sqrt{10}$ . To find the product of this two values, the following steps must be followed.

According to one of the law of indices, $\sqrt{a} = a^{\frac{1}{2} }$

$\sqrt{10} * \sqrt{10}\\= 10^{\frac{1}{2} }* 10^{\frac{1}{2} }\\= 10^{\frac{1}{2}+\frac{1}{2}}\\ = 10^{1} \\= 10$

The product is 10

3 0

3 years ago

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