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3 years ago

−8(y 9)=−40 what does y equal

Mathematics

2 answers:

rewona [7]3 years ago

3 0

-8(y 9) = -40

-72y = -40

y = 40/72 = 5/9

Tpy6a [65]3 years ago

3 0

Answer:

it actual -4

Step-by-step explanation:

i just know ok

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A 15-ft ladder leans against a wall. The lower end of the ladder is being pulled away from the wall at the rate of 1.5 ft/sec. L

Aleks [24]

Answer:

The top of the ladder is sliding down at a rate of 2 feet per second.

Step-by-step explanation:

Refer the image for the diagram. Consider $\Delta ABC$ as right angle triangle. Values of length of one side and hypotenuse is given. Value of another side is not known. So applying Pythagoras theorem,

$\left ( AB \right )^{2}+\left ( BC \right )^{2}=\left ( AC \right )^{2}$

From the given data, $L=15\:ft=AC$ , $y=9\:ft=AB$ and $x=BC$

Substituting the values,

$\therefore \left ( 9 \right )^{2}+\left ( x \right )^{2}=\left ( 15 \right )^{2}$

$\therefore 81+x^{2}=225$

$\therefore x^{2}=225-81$

$\therefore x^{2}=144$

$\therefore \sqrt{x^{2}}=\sqrt{144}$

$\therefore x=\pm 12$

Since length can never be negative, so $x= 12$ .

Now to calculate $\dfrac{dy}{dt}$ again consider following equation,

$\left ( y \right )^{2}+\left ( x \right )^{2}=\left ( l \right )^{2}$

Differentiate both sides of the equation with respect to t,

$\dfrac{d}{dt}\left(y^2+x^2\right)=\dfrac{d}{dt}\left(l^2\right)$

Applying sum rule of derivative,

$\dfrac{d}{dt}\left(y^2\right)+\dfrac{d}{dt}\left(x^2\right)=\dfrac{d}{dt}\left(l^2\right)$

$\dfrac{d}{dt}\left(y^2\right)+\dfrac{d}{dt}\left(x^2\right)=\dfrac{d}{dt}\left(225\right)$

Applying power rule of derivative,

$2y\dfrac{dy}{dt}+2x\dfrac{dx}{dt}=0$

Simplifying,

$y\dfrac{dy}{dt}+x\dfrac{dx}{dt}=0$

Substituting the values,

$9\dfrac{dy}{dt}+12\times1.5=0$

$9\dfrac{dy}{dt}+18=0$

Subtracting both sides by 18,

$9\dfrac{dy}{dt}=-18$

Dividing both sides by 9,

$\dfrac{dy}{dt}= - 2$

Here, negative indicates that the ladder is sliding in downward direction.

$\therefore \dfrac{dy}{dt}= 2\:\dfrac{ft}{sec}$

7 0

3 years ago

Can someone please help me?

Fed [463]

Answer:

yes

Step-by-step explanation:

3 0

3 years ago

Solve the equation 3(2x+2)=3x-15<br>x=-7<br>x=-17/3<br>x=3<br>x=7

Nady [450]

3(2x+2)=3x-15

mutiply the bracket by 3

(3)(2x)(3)(2)= 6x+6

6x+6= 3x-15

move 3x to the other side

sign changes from +3x to -3x

6x-3x+6= 3x-3x-15

6x-3x+6= -15

3x+6= -15

move +6 to the other side

sign changes from +6 to -6

3x+6-6= -15-6

3x= -21

divide by 3 for both sides

3x/3= -21/3

x= -7

Answer: x= -7

4 0

4 years ago

Read 2 more answers

How many half inch tiles would you need to cover the top of a 7 1/2 by 5 1/2 box

enot [183]

165
7.5 and 5.5 goes to 15x11, and that's your answer. 165.

7 0

3 years ago

Simplify the expression. 7m^3 + 2 3/4 - 6m^3

Greeley [361]

Answer:

m^3 + 2 3/4

Step-by-step explanation:

Change the order

7m^3 - 6m^3 + 2 3/4

m^3 + 2 3/4

5 0

3 years ago