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3 years ago

Only do number 19 vote you brainiest

Mathematics

1 answer:

lesya [120]3 years ago

6 0

Answer:

I think 5/12 of them are in 8th grade

Step-by-step explanation:

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Dwayne drove 18 miles to the airport to pick up his father and then returned home. On the return trip he was able to drive an av

Nesterboy [21]

Answer:

30 mph

Step-by-step explanation:

Let d = distance (in miles)

Let t = time (in hours)

Let v = average speed driving <u>to</u> the airport (in mph)

⇒ v + 15 = average speed driving <u>from</u> the airport (in mph)

Using: distance = speed x time

$\implies t=\dfrac{d}{v}$

Create two equations for the journey to and from the airport, given that the distance one way is 18 miles:

$\implies t=\dfrac{18}{v} \ \ \textsf{and} \ \ t=\dfrac{18}{v+15}$

We are told that the total driving time is 1 hour, so the sum of these expressions equals 1 hour:

$\implies \dfrac{18}{v} +\dfrac{18}{v+15}=1$

Now all we have to do is solve the equation for v:

$\implies \dfrac{18(v+15)}{v(v+15)} +\dfrac{18v}{v(v+15)}=1$

$\implies \dfrac{18(v+15)+18v}{v(v+15)}=1$

$\implies 18(v+15)+18v=v(v+15)$

$\implies 18v+270+18v=v^2+15v$

$\implies v^2-21v-270=0$

$\implies (v-30)(v+9)=0$

$\implies v=30, v=-9$

As v is positive, v = 30 only

So the average speed driving to the airport was 30 mph

(and the average speed driving from the airport was 45 mph)

8 0

1 year ago

Read 2 more answers

What is the solution set for this inequality? -8x-40 (greater than) -16

Ulleksa [173]

Answer:

x < -3

Step-by-step explanation:

4 0

3 years ago

Please help asap i am timed will give brainliest

wariber [46]

Answer

Step-by-step explanation:

4 0

2 years ago

Help please this is so hard I don't understand it

Zina [86]

Answer:

<ABC = 15

< BAC = 150

Step-by-step explanation:

<C = <B since this is an isosceles triangle. We know this because AC = AB

<C = 15 so <ABC = 15

The sum of the angles of a triangle is 180

A + B+ C = 180

A + 15+15 = 180

A +30 =180

A = 180-30

A = 150

< BAC = 150

5 0

3 years ago

Y= − 2 ( x − 2 ) ( x + 8 ) −2(x−2)(x+8) in standard form

Harlamova29_29 [7]

Answer:

$y=-4x^{2} -24x+64$

Step-by-step explanation:

$y=-2(x-2)(x+8)-2(x-2)(x+8)$

$y=-2x^{2} +12x+32-2(x-2)(x+8)$

$y=-2x^{2} -12x+32-2x^{2} -12x+32$

$y=-4x^{2} -24x+64$

7 0

3 years ago