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3 years ago

Alfonso runs 10 km at an average speed of x km/h.

Mathematics

1 answer:

puteri [66]3 years ago

6 0

Step-by-step explanation:

Note that t = d/r where t is time, d is distance, and r is rate/speed.

We can come up with two equations with the information given and the equation:

t_1 hr = (10 km)/(x km/hr)

t_2 hr = (12 km)/(x - 1 km/hr)

where t_1 is the time taken to run the 10km the first day and t_2 is the time taken to run the 12km the second day.

We know that 30 minutes is 1/2 of an hour and that t_1 is 30 minutes less than t_2 (as stated in the question). Therefore, we can write:

t_1 = t_2 - 1/2

Substituting the values we derived:

(10 km)/(x km/hr) = (12 km)/(x - 1 km/hr) -1/2

Then we can evaluate by multiplying by 2x(x-1) on both sides:

20(x-1) = 24x - (x)(x-1)

20x - 20 = 24x - x^2 + x

x^2 -5x -20 = 0

And we are done.

I hope this helps! :)

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Question 4 pleaseeeeeee

arsen [322]

Answer:

Step-by-step explanation:

Unit rate means one quantity in terms of another unit quantity. In the answer choices, we see that the denominator is always in terms of UNIT LITERS (1 L), so that means, we have to find gallons in terms of UNIT LITERS.

It means, we have to divide gallons by liters to get in terms of unitary liters.

Let's check the first line:

19.5/75 = 0.26 Gallons / 1 Liter

Now, checking 2nd:

39/150 = 0.26 Gallons / 1 Liter

So, yes, they are the same and other 2 lines would be the same as well. The unit rate is:

0.26 gal/1L

That's answer choice B

7 0

3 years ago

Can someone help please thanks

LuckyWell [14K]

blue with green is 5/10 green and red 3/10 both red 2/10 both blue 4/10

3 0

3 years ago

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A 1200 b 3200 c 3680 d 5520

anygoal [31]

Answer:

c. 3680

Step-by-step explanation:

In 2010, the population was 8000.

In 2014, it increased by 15%.

Population in 2014 :

= 8000 + 15/100×8000

= 8000 + 1200

= 9200.

Now, 2/5 of the population was age 12 or under.

= 2/5 × 9200

= 2×1840

= 3680

Answer - c) 3680

3 0

3 years ago

Temperature in degrees Fahrenheit can be converted into degrees Celsius using the formula C=5(F-32)/9

aksik [14]

Answer:

F= (9C+160)/5

Step-by-step explanation:

C=5(F-32)/9

make F the subject of the formula= isolate F

5(F-32)=9C

5F-160=9C

5F=9C+160

F= (9C+160)/5

check: a, b, c are all positive integers (a=9, b=160, c=5)

8 0

3 years ago

The hypotenuse of a right triangle has endpoints A(4, 1) and B(–1, –2). On a coordinate plane, line A B has points (4, 1) and (n

GarryVolchara [31]

Answer:

$(-1,1),(4,-2)$

Step-by-step explanation:

Given: The hypotenuse of a right triangle has endpoints A(4, 1) and B(–1, –2).

To find: coordinates of vertex of the right angle

Solution:

Let C be point $(x,y)$

Distance between points $(x_1,y_1),(x_2,y_2)$ is given by $\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$

$AC=\sqrt{(x-4)^2+(y-1)^2}\\BC=\sqrt{(x+1)^2+(y+2)^2}\\AB=\sqrt{(4+1)^2+(1+2)^2}=\sqrt{25+9}=\sqrt{34}$

ΔABC is a right angled triangle, suing Pythagoras theorem (square of hypotenuse is equal to sum of squares of base and perpendicular)

$34=\left [ (x-4)^2+(y-1)^2 \right ]+\left [ (x+1)^2+(y+2)^2 \right ]$

Put $(x,y)=(-1,1)$

$34=\left [ (-1-4)^2+(1-1)^2 \right ]+\left [ (-1+1)^2+(1+2)^2 \right ]\\34=25+9\\34=34$

which is true. So, $(-1,1)$ can be a vertex

Put $(x,y)=(4,-2)$

$34=\left [ (4-4)^2+(-2-1)^2 \right ]+\left [ (4+1)^2+(-2+2)^2 \right ]\\34=9+25\\34=34$

which is true. So, $(4,-2)$ can be a vertex

Put $(x,y)=(1,1)$

$34=\left [ (1-4)^2+(1-1)^2 \right ]+\left [ (1+1)^2+(1+2)^2 \right ]\\34=9+4+9\\34=22$

which is not true. So, $(1,1)$ cannot be a vertex

Put $(x,y)=(2,-2)$

$34=\left [ (2-4)^2+(-2-1)^2 \right ]+\left [ (2+1)^2+(-2+2)^2 \right ]\\34=4+9+9\\34=22$

which is not true. So, $(2,-2)$ cannot be a vertex

Put $(x,y)=(4,-1)$

$34=\left [ (4-4)^2+(-1-1)^2 \right ]+\left [ (4+1)^2+(-1+2)^2 \right ]\\34=4+25+1\\34=30$

which is not true. So, $(4,-1)$ cannot be a vertex

Put $(x,y)=(-1,4)$

$34=\left [ (-1-4)^2+(4-1)^2 \right ]+\left [ (-1+1)^2+(4+2)^2 \right ]\\34=25+9+36\\34=70$

which is not true. So, $(-1,4)$ cannot be a vertex

So, possible points for the vertex are $(-1,1),(4,-2)$

7 0

3 years ago

Read 2 more answers