All categories

3 years ago

-9x2 + 13x – 1=0 I need 3 answers, pls help me:)

Mathematics

1 answer:

kifflom [539]3 years ago

5 0

The answer to this question is x = 13/9 = 1.444

You might be interested in

Find the absolute maximum and absolute minimum values of the function f(x, y) = x 2 + y 2 − x 2 y + 7 on the set d = {(x, y) : |

dsp73

Looks like $f(x,y)=x^2+y^2-x^2y+7$ .

$f_x=2x-2xy=0\implies2x(1-y)=0\implies x=0\text{ or }y=1$

$f_y=2y-x^2=0\implies2y=x^2$

If $x=0$ , then $y=0$ - critical point at (0, 0).
If $y=1$ , then $x=\pm\sqrt2$ - two critical points at $(-\sqrt2,1)$ and $(\sqrt2,1)$

The latter two critical points occur outside of $D$ since $|\pm\sqrt2|>1$ so we ignore those points.

The Hessian matrix for this function is

$H(x,y)=\begin{bmatrix}f_{xx}&f_{xy}\\f_{yx}&f_{yy}\end{bmatrix}=\begin{bmatrix}2-2y&-2x\\-2x&2\end{bmatrix}$

The value of its determinant at (0, 0) is $\det H(0,0)=4>0$ , which means a minimum occurs at the point, and we have $f(0,0)=7$ .

Now consider each boundary:

If $x=1$ , then

$f(1,y)=8-y+y^2=\left(y-\dfrac12\right)^2+\dfrac{31}4$

which has 3 extreme values over the interval $-1\le y\le1$ of 31/4 = 7.75 at the point (1, 1/2); 8 at (1, 1); and 10 at (1, -1).

If $x=-1$ , then

$f(-1,y)=8-y+y^2$

and we get the same extrema as in the previous case: 8 at (-1, 1), and 10 at (-1, -1).

If $y=1$ , then

$f(x,1)=8$

which doesn't tell us about anything we don't already know (namely that 8 is an extreme value).

If $y=-1$ , then

$f(x,-1)=2x^2+8$

which has 3 extreme values, but the previous cases already include them.

Hence $f(x,y)$ has absolute maxima of 10 at the points (1, -1) and (-1, -1) and an absolute minimum of 0 at (0, 0).

3 0

3 years ago

X + y - z = - 2, 2x - y + z = 8, - x + 2y + 2z = 10

Maurinko [17]

Answer:

Step-by-step explanation:

3 0

2 years ago

You pick a marble and spin the spinner. How many outcomes are possible?

grigory [225]

Answer:

4 i think

Step-by-step explanation:

can you go one question to the left i need help

6 0

3 years ago

Today the 6th graders had 5 students absent, the 7th graders had 8 students absent,and the 8th graders had 9 students absent. If

Irina18 [472]

All you have to do is multiply 8 by 20 which is 160

7 0

3 years ago

Consider the set of points defined by z = 5 cos(theta) + 3i sin(theta).

vitfil [10]

Answer:

This is an ellipse.

Step-by-step explanation:

$z=5cos(\theta)+3isin(\theta)$

Applying the angle values in intervals of right angles (90°), the resulting set of values for z are:

$\theta = 0,90,180,270,360$

$z=5,3i,-5,-3i,5$ (again)

If you look at the plot, you will observe how these values represent points in the xy plain. All of them belong to either the x or the y axis.

The resulting figure for the whole set of values of $\theta$ is in fact an ellipse.

4 0

3 years ago