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3 years ago

Whats the Y coordinate Of the solution to the system of equations 4x-4=-2y 2x-y=8

Mathematics

1 answer:

MakcuM [25]3 years ago

5 0

I am going to be honest with you on this one, but this one is really really really hard to answer

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katen-ka-za [31]

Answer:

3.7 and east.

Step-by-step explanation:

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3 years ago

An 8 foot length of 4 inch wide crown molding costs $16. How much will it cost to buy 40 feet of crown molding?

malfutka [58]

Converting feet to inches, 8*12=96 and 96*4=384. Next, 40*12=480. Since 384*x (if x represents the cost per inch of crown molding)=16*100=1600 cents due to that for every inch, we add x amount of money, we can find x to be 1600/384=800/192=400/96=200/48=100/24=50/12=25/6 by simply dividing both the numerator and denominator by 2 each time. Since we add x amount of money for every inch, and we have 480 inches, 480*x=480*25/6=2000 cents=2000/100=20 dollars is our answer

6 0

3 years ago

An airplane flew 4 hours with a 25 mph tail wind. The return trip against the same wind took 5 hours. Find the speed of the airp

balu736 [363]

Answer:

r = 225 Mil/h speed of the airplane in still air

Step-by-step explanation:

Then:

d is traveled distance and r the speed of the airplane in still air

so the first equation is for a 4 hours trip

as d = v*t

d = 4 * ( r + 25) (1) the speed of tail wind (25 mil/h)

Second equation the trip back in 5 hours

d = 5 * ( r - 25 ) (2)

So we got a system of two equation and two unknown variables d and

We solve it by subtitution

from equation (1) d = 4r + 100

plugging in equation 2

4r + 100 = 5r - 125 ⇒ -r = -225 ⇒ r = 225 Mil/h

And distance is :

d = 4*r + 100 ⇒ d = 4 * ( 225) + 100

d = 900 + 100

d = 1000 miles

6 0

3 years ago

Please help and graph it I need this done in 2 minut s pleasee

My name is Ann [436]

Go to a website called desmos it’s a graphing calculator and you just type what you want graphed and it shows it

3 0

3 years ago

How to find the derivative of cos^2x? i seem to be confused.

slamgirl [31]

If you're using the app, try seeing this answer through your browser: brainly.com/question/2927231

————————

You can actually use either the product rule or the chain rule for this one. Observe:

• Method I:

y = cos² x

y = cos x · cos x

Differentiate it by applying the product rule:

$\mathsf{\dfrac{dy}{dx}=\dfrac{d}{dx}(cos\,x\cdot cos\,x)}\\\\\\
\mathsf{\dfrac{dy}{dx}=\dfrac{d}{dx}(cos\,x)\cdot cos\,x+cos\,x\cdot \dfrac{d}{dx}(cos\,x)}$

The derivative of cos x is – sin x. So you have

$\mathsf{\dfrac{dy}{dx}=(-sin\,x)\cdot cos\,x+cos\,x\cdot (-sin\,x)}\\\\\\
\mathsf{\dfrac{dy}{dx}=-sin\,x\cdot cos\,x-cos\,x\cdot sin\,x}$

$\therefore~~\boxed{\begin{array}{c}\mathsf{\dfrac{dy}{dx}=-2\,sin\,x\cdot cos\,x}\end{array}}\qquad\quad\checkmark$

—————

• Method II:

You can also treat y as a composite function:

$\left\{\!
\begin{array}{l}
\mathsf{y=u^2}\\\\
\mathsf{u=cos\,x}
\end{array}
\right.$

and then, differentiate y by applying the chain rule:

$\mathsf{\dfrac{dy}{dx}=\dfrac{dy}{du}\cdot \dfrac{du}{dx}}\\\\\\
\mathsf{\dfrac{dy}{dx}=\dfrac{d}{du}(u^2)\cdot \dfrac{d}{dx}(cos\,x)}$

For that first derivative with respect to u, just use the power rule, then you have

$\mathsf{\dfrac{dy}{dx}=2u^{2-1}\cdot \dfrac{d}{dx}(cos\,x)}\\\\\\
\mathsf{\dfrac{dy}{dx}=2u\cdot (-sin\,x)\qquad\quad (but~~u=cos\,x)}\\\\\\
\mathsf{\dfrac{dy}{dx}=2\,cos\,x\cdot (-sin\,x)}$

and then you get the same answer:

$\therefore~~\boxed{\begin{array}{c}\mathsf{\dfrac{dy}{dx}=-2\,sin\,x\cdot cos\,x}\end{array}}\qquad\quad\checkmark$

I hope this helps. =)

Tags: <em>derivative chain rule product rule composite function trigonometric trig squared cosine cos differential integral calculus</em>

3 0

3 years ago