Mathematics, 19.10.2021 20:40 jojonono

Justin recently drove to visit his parents who live 96 miles away. On his way there his average speed was 20 miles per hour faster than on his way home (he ran into some bad weather). If Justin spent a total of 4 hours driving, find the two rates (in mph). Round your answer to two decimal places, if needed. Justin's average speed to his parents' house: mph

Justin's average speed from his parents' house: mph

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Answer from: thesusan56351

Justin's average speed to his parents' house: x= 40mph

Justin's average speed from his parents' house: x+20=60 mph

Step-by-step explanation:

Let the average speed be x +20

Then average speed from his parents' x

And the distance is S=96

Then we know :

$\displaystyle \frac{S}{x+20} +\frac{S}{x} =4 \\\\\\ \frac{96}{x+20} +\frac{96}{x}=4 \ |\div 4 \\\\\\ 24\bigg(\frac{1}{x+20} +\frac{1}{x} \bigg) =1 \\\\\\ 24\cdot \frac{x+x+20}{(x+20)x} =1 \ |\cdot (x+20)x \ \ \\\\\\48x+480=x^2+20x \\\\ x^2-28x-480=0 \\\\ \rm D=28^2+4\cdot 480=2704 =52^2 \\\\ \boxed{x_1=\frac{28+52}{2} =40} \\\\x_2=\frac{28-52}{2} =-12 \ \ \varnothing$

Justin's average speed to his parents' house: x= 40mph

Justin's average speed from his parents' house: x+20=60 mph

Answer from: deepspy599otchpd

$\huge\textsf{Answer}$

Outward bound::

rate = x+9 ; dist = 100 m ; time = 100/(x+9) hrs

----

Homeward

rate = x mph ; dist = 100 m ; time = 100/x hrs

=======

Equation:

time + time = 5 hrs

100/(x+9) + 100/x = 5 hrs

----

100x + 100(x+9) = 5x(x+9)

----

200x + 900 = 5x^2 + 45x

5x^2 - 155x - 900 = 0

-----

x^2 - 31x - 180 = 0

-----

x = 36 mph

x+9 = 45 mph

------

so x=40km

and average speed=x+20=60mph

Answer from: Quest

what is the graph

step-by-step explanation:

Answer from: Quest

step-by-step explanation: the declaration of the rights of man and of the citizen (french: déclaration des droits de l'homme et du citoyen de 1789), set by france's national constituent assembly in 1789, is a human civil rights document from the french revolution.[1]

the declaration was drafted by the abbé sieyès and the marquis de lafayette, in consultation with thomas jefferson.[2] influenced by the doctrine of "natural right", the rights of man are held to be universal: valid at all times and in every place, pertaining to human nature itself. it became the basis for a nation of free individuals protected equally by the law. it is included in the beginning of the constitutions of both the fourth french republic (1946) and fifth republic (1958) and is still current. inspired by the enlightenment philosophers, the declaration was a core statement of the values of the french revolution and had a major impact on the development of freedom and democracy in europe and worldwide.[3]

the 1789 declaration, together with the 1215 magna carta, the 1689 english bill of rights (1689), the 1776 united states declaration of independence, and the 1789 united states bill of rights, inspired in large part the 1948 united nations universal declaration of human rights

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Justin recently drove to visit his parents who live 96 miles away. On his way there his average spee...