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4 years ago

5.

Mathematics

1 answer:

lana [24]4 years ago

3 0

Answer:

Step-by-step explanation:

a) +200

b) - 200

c) -500m {well is below sea level.For bellow sea level use - sign}

d) + 5000m

6) a) 12 - 3x

b) (x +10)/7

c) -5y + 16

d) 2m - 11

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7. Given the systems below, state how many solutions there are. YOU MUST GIVE A REASON

Dmitry [639]

In a there will be 1 solution as 7x and 5x + 2 is the same and in b there will be 2 solutions as they both are 2 different questions hope this helped

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3 years ago

Help please...............

frozen [14]

Answer:

Sam made a mistake, and their correct value is 30.

Step-by-step explanation:

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3 years ago

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What is the second step in the process for factoring the trinomial x^2-3x-40

krek1111 [17]

Answer:

You make a factor tree for (-)40 where the factors of -40 are -8 and +5. This becomes (x+5)(x-8) which can be multiplied to get back to the starting point.

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3 years ago

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A girl starts to walk to her school, which is 20 miles away, at 6:50 and at a rate of 3 miles per hour. After a while, her dad p

Alexeev081 [22]

The girl walked a distance of $\boxed{{\mathbf{5 miles}}}$ in her way.

Further explanation:

The time can be calculated as,

${\text{ time}}=\frac{{{\text{distance}}}}{{{\text{speed}}}}$

Given:

It is given that a girl stands 20 miles away from the school at $6:50{\text{ am}}$ and she started walking at the rate of $3{\text{ mi/hr}}$ and then after some time her dad pick up and he drives at the rate of $30{\text{ mi/hr}}$ . They reach the school at $9:00{\text{ am}}$ .

Step by step explanation:

Step 1:

Consider $x$ as the distance she walked in her way.

The speed of the girl when she walked is $3{\text{ mi/hr}}$ .

Now use the formula of time to obtain the walk time.

$\begin{gathered}{\text{ walktime}}=\frac{{{\text{distance walked}}}}{{{\text{walking speed}}}}\hfill\\{\text{ walktime}}=\frac{x}{3}\hfill\\\end{gathered}$

Since the total distance is $20{\text{ miles}}$ .

Then consider $20-x$ as the distance driven by the car.

The driving speed is $30{\text{ mi/hr}}$ .

Now use the formula of time to obtain the drive time.

$\begin{gathered}{\text{drive time}}=\frac{{{\text{distance travelled by car }}}}{{{\text{ speed of car}}}}\hfill\\{\text{drive time}}=\frac{{20-x}}{{30}} \hfill\\\end{gathered}$

Step 2:

Now we calculate the total time took by girl to reach the school.

$9:00-6:50={\text{2 hrs 10 min}}$

Now convert the timing into hours as,

$\begin{aligned}2{\text{ hours 10 minutes}}&=2+\frac{{10}}{{60}}\\&=2\frac{1}{6}\\&=\frac{{13}}{6}{\text{ hrs}}\\\end{aligned}$

Step 3:

Total time is the sum of drive time and walk time.

The total time can be expressed as,

$\frac{x}{3}+\frac{{20-x}}{{30}}=\frac{{13}}{6}$

Now solve the above equation by cross multiply method.

$\begin{aligned}\frac{x}{3}+\frac{{20-x}}{{30}}&=\frac{{13}}{6}\hfill\\\frac{{10x+20-x}}{{30}}&=\frac{{13}}{6}\hfill\\\frac{{9x+20}}{{30}}&=\frac{{13}}{6}\hfill\\6\left({9x+20}\right)&=13\left({30}\right)\hfill\\\end{aligned}$

Now simplify the further equation.

$\begin{aligned}6\left({9x+20}\right)&=13\left({30}\right)\hfill\\54x+120&=390\hfill\\54x&=390-120\hfill\\54x&=270\hfill\\\end{aligned}$

Simplify the further equation.

$\begin{aligned}54x&=270\hfill\\x&=\frac{{270}}{{54}}\hfill\\x&=\frac{{45}}{9}\hfill\\x&=5\hfill\\\end{gathered}$

Therefore, the girl walked 5 miles.

Learn more:

Learn more about the distance between the points brainly.com/question/6278187

Learn more about the equivalent fraction brainly.com/question/952259

Learn more about midpoint of the segment brainly.com/question/3269852

Answer details:

Grade: High school

Subject: Mathematics

Chapter: Speed, distance and time

Keywords: girl, distance, drive, walk, drive time, dad, speed, travelled, formula, cross multiply, fraction, number, multiply, addition, subtraction, equation, school

8 0

4 years ago

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Imagine you had 40 one-metre sections of fencing.

Darya [45]

Answer: If I’m not mistaken, the largest area is 75 m2 and the smallest is 2 m2

Step-by-step explanation:

For both : since they are asking for the area, you should calculate the perimeter.

So for the largest area, since you know that you have 40 fences, and each are 1 meter long, and they’re also asking for the largest rectangular area, this means that only the opposite sides will have the same length, so in order to divide the rectangle with the 40 one-meter fences, the biggest sides have to be 15 meters long (so for both : 15x2=30 meters). Then you deduct from 40, 30 : 40-30 = 10 which then you can devide by 2 and find 5 + 5 and that means that the 2 smallest sides will be 5 meters long each. Then finally to calculate the perimeter you should do the biggest side multiplied by the smallest side : 15 x 5 and you find 75 m2 (squaremeters), if I’m not mistaken.

And for the smallest area you take the smallest possibilities knowing that only the opposite sides should have the same length and not all of them, so you do 1 x 2 and you find 2 m2.

8 0

4 years ago