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3 years ago

How would you do number 12 and 15?

Mathematics

1 answer:

Gnesinka [82]3 years ago

7 0

Answer:

$x_1=x_2=-\dfrac{2}{3}$

Step-by-step explanation:

For the quadratic equation $ax^2+bx+c=0$ the discriminant is defined as

$D=b^2-4ac$

and the quadratic formula for the roots gives us two roots:

$x_1=\dfrac{-b-\sqrt{D}}{2a}$

and

$x_2=\dfrac{-b+\sqrt{D}}{2a}$

For the equation $9x^2 +12x+4=0$ use quadratic formula to find roots:

$D=12^2-4\cdot 9\cdot 4=144-144=0$

So,

$x_1=x_2=\dfrac{-12\pm \sqrt{0}}{2\cdot 9}=-\dfrac{12}{18}=-\dfrac{2}{3}$

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The point P(1,1/2) lies on the curve y=x/(1+x). (a) If Q is the point (x,x/(1+x)), find the slope of the secant line PQ correct

lukranit [14]

Answer:

See explanation

Step-by-step explanation:

You are given the equation of the curve

$y=\dfrac{x}{1+x}$

Point $P\left(1,\dfrac{1}{2}\right)$ lies on the curve.

Point $Q\left(x,\dfrac{x}{1+x}\right)$ is an arbitrary point on the curve.

The slope of the secant line PQ is

$\dfrac{y_2-y_1}{x_2-x_1}=\dfrac{\frac{x}{1+x}-\frac{1}{2}}{x-1}=\dfrac{\frac{2x-(1+x)}{2(x+1)}}{x-1}=\dfrac{\frac{2x-1-x}{2(x+1)}}{x-1}=\\ \\=\dfrac{\frac{x-1}{2(x+1)}}{x-1}=\dfrac{x-1}{2(x+1)}\cdot \dfrac{1}{x-1}=\dfrac{1}{2(x+1)}\ [\text{When}\ x\neq 1]$

1. If x=0.5, then the slope is

$\dfrac{1}{2(0.5+1)}=\dfrac{1}{3}\approx 0.3333$

2. If x=0.9, then the slope is

$\dfrac{1}{2(0.9+1)}=\dfrac{1}{3.8}\approx 0.2632$

3. If x=0.99, then the slope is

$\dfrac{1}{2(0.99+1)}=\dfrac{1}{3.98}\approx 0.2513$

4. If x=0.999, then the slope is

$\dfrac{1}{2(0.999+1)}=\dfrac{1}{3.998}\approx 0.2501$

5. If x=1.5, then the slope is

$\dfrac{1}{2(1.5+1)}=\dfrac{1}{5}\approx 0.2$

6. If x=1.1, then the slope is

$\dfrac{1}{2(1.1+1)}=\dfrac{1}{4.2}\approx 0.2381$

7. If x=1.01, then the slope is

$\dfrac{1}{2(1.01+1)}=\dfrac{1}{4.02}\approx 0.2488$

8. If x=1.001, then the slope is

$\dfrac{1}{2(1.001+1)}=\dfrac{1}{4.002}\approx 0.2499$

7 0

3 years ago

Write the standard form of the equation for the circle that passes through the points (2,31),(-15,14),(33,0)

stepladder [879]

Answer:

Step-by-step explanation:

Begin with the standard form of a circle as a conic:

$Ax^2+Bxy+Cy^2+Dx+Ey+F=0$

For a circle, A and C will be the exact same, and B will equal 0. If B is non-zero, the equation represents a rotation of a conic, which is reserved for college-level courses. Shortening this, then:

$x^2+y^2+Dx+Ey+F=0$ is good enough for us for this. Start with the first point on the circle, (2, 31) and fill in the equation above with x and y:

$2^2+31^2+2D+31E+F=0$ which simplifies down to:

$(1):2D+31E+F=-965$

Do the same with the next point on the circle, (-15, 14):

$-15^2+14^2-15D+14E+F=0$ which simplifies down to:

$(2):-15D+14E+F=0$

Do the same with the last point, (33, 0):

$33^2+0^2+33D+0E+F=0$ which simplifies down to:

$(3):33D+F=-1089$

Now we will add (1) and (2) to get (4):

2D + 31E + F = -965

-15D + 14E + F = -421

Multiply the top equatio by -1 to get rid of the F terms:

-2D - 31E - F = 965

-15D + 14E + F = -421

which simplifies to

(4): -17D - 17E = 544

Now add (2) and (3) to get (5):

-15D + 14E + F = -421

33D + F = -1089

Multiply the bottom equation by -1 to get rid of the F terms:

-15D + 14E + F = -421

-33D - F = 1089

which simplifies to

(5): -48D + 14E = 668

Now add (4) and (5) together and eliminate the E terms:

-17D - 17E = 544

-48D + 14E = 668

In order to eliminate the E terms, multiply the top equation by 14 and the bottom equation by 17 to solve for D:

-238D - 238E = 7616

-816D + 238E = 11356

Which gives you that

D = -18

Now plug the value for D into (4) to find E:

-17(-18) - 17E = 544 and

306 - 17E = 544 and

-17E = 238 so

E = -14

Now plug the values for both D and E into (1) to find F:

2(-18) + 31(-14) + F = -965 and

-36 - 434 + F = -965 and

-470 + F = -965 so

F = -495

Now we can fill in the standard form of the conic:

$x^2+y^2-18x-14y=495$

but we're not done til we complete the square on both the x terms and the y terms (and I am assuming you know how to complete the square):

$(x^2-18x+81)+(y^2-14y+49)=495+81+49$ which simplifies to

$(x-9)^2+(y-7)^2=625$

The second choice down matches that equation, but the center they have there is not correct. The center of that circle is (9, 7) and they have it as being (7, 10) with a radius of 5. The radius is 25. The center is wrong in the equation that represents the circle as is the radius. Maybe let someone know that...

4 0

3 years ago

Read 2 more answers

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igor_vitrenko [27]

He made a profit of thirty dollars

8 0

3 years ago

Read 2 more answers

Convert the following decimal to a percentege!!!!!! brainlest too

AfilCa [17]

Answer:

8.61%

61.29%

14.86%

20%

Step-by-step explanation:

8 0

2 years ago

What is the answer some one help me please so i can do this

inna [77]

Answer:

They can buy up to 240 drinks.

Step-by-step explanation:

Let x = number of drinks

The price of 1 drink is 75¢ = $0.75

The price of x drinks is 0.75x

The store gives a discount of $100.

The rice of x drinks is

0.75x - 100

The total price of the drinks must be less than or equal to $80.

0.75x - 100 ≤ 80

Add 100 to both sides.

0.75x ≤ 180

Divide both sides by 0.75

x ≤ 240

Answer: They can buy up to 240 drinks.

6 0

2 years ago