Toán cao cấp, giải tích..............

Youssef can either way from his home to his workplace or ride his bicycle. he walks at a pace of 1 block per min, but he can tra

alex41 [277]

Youssef lives 15 blocks away from his work

Solution:

Given that Youssef can either way from his home to his workplace or ride his bicycle

Let "x" be number of blocks away from work Youssef works

Case 1: walking

He walks at a pace of 1 block per min

Therefore,

1 block = 1 minute

Thus to cross "x" blocks he takes "x" minutes

Case 2: Bicycle

He can travel 1 block in 20 sec on his bicycle

We know that,

To convert seconds to minute, divide the time value by 60

$\rightarrow 20 seconds = \frac{20}{60} minutes = \frac{1}{3} minutes$

Thus he takes 1/3 minutes for 1 block

So to cross "x" blocks he will take $\frac{x}{3}$ minutes

Given that it takes youssef 10 min longer to walk to work than to ride his bike

This means difference between time taken to cross "x" blocks by walking and ride by bicycle is 10 minutes

$\rightarrow x - \frac{x}{3} = 10\\\\\rightarrow \frac{3x - x}{3} = 10\\\\\rightarrow \frac{2x}{3} = 10\\\\\rightarrow x = \frac{30}{2}\\\\\rightarrow x = 15$

Thus he lives 15 blocks away from his work

4 0

3 years ago

Solve the system of equations using the substitution method.

Karolina [17]

Substitution is where we first Isolate one of the unknowns, express it in terms of the other unknown, and replace the isolated unknown with the other unknown in another equation. So that each time we only need to deal with one unknown. I think you'll get a better idea here:

First name these 2 equations with 1 and 2.
4x + 5y = 7 (1)
y = 3x + 9 (2)

Since y is already isolated in (2), so we can skip the isolation step and continue to substitute.

Substitute (2) into (1).
4x + 5(3x+9) = 7

Expand.
4x + 15x + 45 = 7

Group.
19x + 45 = 7

Shift +45 to the other side and turn it into -45.

19x = 7 - 45
19x = -38

Shift x19 to the other side, turn it into /19.
X = - 38/19
X = - 2

Now we solved x already, we can just substitute x= - 2 back to equation (2).

y = 3(-2) + 9
y = - 6 + 9
y = 3

So, the answers are
x = - 2
y = 3

3 0

2 years ago

3. Marcus had an average score of 90% on two biology tests about protists. If his first test score was 96%, which score did he r

Maurinko [17]

Answer:

B: 84%

Step-by-step explanation:

7 0

2 years ago

A Japanese bullet train travels 558 miles per 3 hours A. What is the rate B. How far does the train travel in 1 hour WHO EVER A

Delicious77 [7]

Answer:

Step-by-step explanation:

Remark

The rate is going to be the same as the distance travelled in 1 hour. The units will be different.

Formula

d = r * t

Givens

d = 558 miles

t = 3 hours

Problem A

r = d / t

r = 558/ 3 = 186 miles / hr

Problem B

Givens

r = 186 miles / hour

t = 1 hour

d = ?

Solution

d = 186 mi/hr * 1 hr

d = 186 miles

Note

This looks really trivial, but it's not. You have to learn to see the difference between a number and its units. It's not very often that the numbers will be the same, but if the units differ, then it is an entirely different question.

7 0

2 years ago

Write this in order: (greatest to least:) 112 , 100.789 , 101.89 , 101.9 , 190. 1

ruslelena [56]

Answer:

190.1, 101.89, 101.9, 100.789, 112, 1

Step-by-step explanation:

7 0

3 years ago

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