A man loses 30% by selling an article for 14 naira. what was the cost price of the article?

Find the maximum and minimum values of the function f(x,y)=2x2+3y2−4x−5 on the domain x2+y2≤100. The maximum value of f(x,y) is:

ryzh [129]

First find the critical points of f :

$f(x,y)=2x^2+3y^2-4x-5=2(x-1)^2+3y^2-7$

$\dfrac{\partial f}{\partial x}=2(x-1)=0\implies x=1$

$\dfrac{\partial f}{\partial y}=6y=0\implies y=0$

so the point (1, 0) is the only critical point, at which we have

$f(1,0)=-7$

Next check for critical points along the boundary, which can be found by converting to polar coordinates:

$f(x,y)=f(10\cos t,10\sin t)=g(t)=295-40\cos t-100\cos^2t$

Find the critical points of g :

$\dfrac{\mathrm dg}{\mathrm dt}=40\sin t+200\sin t\cos t=40\sin t(1+5\cos t)=0$

$\implies\sin t=0\text{ OR }1+5\cos t=0$

$\implies t=n\pi\text{ OR }t=\cos^{-1}\left(-\dfrac15\right)+2n\pi\text{ OR }t=-\cos^{-1}\left(-\dfrac15\right)+2n\pi$

where n is any integer. We get 4 critical points in the interval [0, 2π) at

$t=0\implies f(10,0)=155$

$t=\cos^{-1}\left(-\dfrac15\right)\implies f(-2,4\sqrt6)=299$

$t=\pi\implies f(-10,0)=235$

$t=2\pi-\cos^{-1}\left(-\dfrac15\right)\implies f(-2,-4\sqrt6)=299$

So f has a minimum of -7 and a maximum of 299.

4 0

3 years ago

Midpoint of the x intercepts of f(x)=(x-4)(x+4)

lorasvet [3.4K]

The x-intercept is defined to be the value of x when y is zero. Based on the graph of the function: f(x) = (x-4)(x+4), the x-intercepts are located at (-4, 0) and (4,0). At these points the graph intersects the x-axis. The midpoint of the x-intercepts is located at the middle of the two points. In this case, the graph shows that it is at the origin or at (0,0).

5 0

3 years ago

Read 2 more answers

Please help <3

Aleksandr [31]

Answer:

x =3

Step-by-step explanation:

3(4x + 4) = 2(5x+9) - 12

First step is to open the brackets by multiplying. It becomes

3×4x + 3×4 = 2×5x + 2×9 -12

12x + 12 = 10x + 18 - 12

Collecting like terms on the right hand side and left hand side of the equation, it becomes

12x -10x = 18 -12 -12

2x = -6

Negative sign on the right hand side of the equation overwhelms the positive sign on left hand side of the equation. It becomes

2x = -6

x = -6/2 = -3

Checking

3(4×-3 + 4) = 2(5×-3+9) - 12

-24 = -12-12= -24

So x = -3

3 0

3 years ago

What is the probability of rolling a 6 sided die and getting a 4 or a number divisible by 3. A) 1/3 B) 1/18 C) 2/3 D) 1/2

KATRIN_1 [288]

Let
Event A = rolling a 4 on a single die
Event B = rolling a number divisible by 3 (3 or 6) on a single die

There are three outcomes possible in total if either event A happens or event B happens. This is out of six outcomes total.

Divide the values and reduce: 3/6 = 1/2

Final Answer: Choice D) 1/2

6 0

3 years ago

Which of the fractions below is closest to 7?

svetoff [14.1K]

Answer:

I think that the awnser is A because I think it is

6 0

2 years ago

A man loses 30% by selling an article for 14 naira. what was the cost price of the article?​

A man loses 30% by selling an article for 14 naira. what was the cost price of the article?