A community for students.
Here's the question you clicked on:
 0 viewing
anonymous
 one year ago
4. If x = 20 when y = 4, find y when x = 10.
anonymous
 one year ago
4. If x = 20 when y = 4, find y when x = 10.

This Question is Closed

ahsome
 one year ago
Best ResponseYou've already chosen the best response.0Is this a linear equation, @dianolove?

ahsome
 one year ago
Best ResponseYou've already chosen the best response.0Wait, couldn't you do: \[\begin{align} y&=kx\\ 4&=k\times20\\ k&=\dfrac{1}{5} \end{align}\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0this is the question it asked me Suppose that x and y vary inversely. Write a function that models each inverse variation. Then use the equation to solve the problem.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0Let's solve your equation stepbystep. 20x−4x=10 Step 1: Simplify both sides of the equation. 20x−4x=10 Simplify: (Show steps) 16x=10 Step 2: Divide both sides by 16. 16x16=1016 x=58 Answer: x=58

phi
 one year ago
Best ResponseYou've already chosen the best response.1*** x and y vary inversely*** means you can write the formula \[ y = \frac{k}{x} \]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0it is a inverse variation and your solving for y not x

phi
 one year ago
Best ResponseYou've already chosen the best response.1that formula is useful if we know what "k" is. to find k, we use the info If x = 20 when y = 4, find y when x = 10.

phi
 one year ago
Best ResponseYou've already chosen the best response.1in other words, replace x with 20 and y with 4 into the formula \[ 4= \frac{k}{20} \] and "solve for k" by multiplying both sides by 20

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes, so now you know the formula (for this problem) is \[ y = \frac{80}{x} \] find y when x = 10. to find y, replace x with 10 in the formula and simplify

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0thanks phi will you keep helping me with these i got another one

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0If x = 5 when , find y when x = 10.

anonymous
 one year ago
Best ResponseYou've already chosen the best response.05. If x = 5 when y=1 third , find y when x = 10.

phi
 one year ago
Best ResponseYou've already chosen the best response.1do you mean if x=5 when y = \(  \frac{1}{3} \) ?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0sorry mines will not do that but yes

phi
 one year ago
Best ResponseYou've already chosen the best response.1you could type it as y= 1/3 \[ y = \frac{k}{x} \\  \frac{1}{3} = \frac{k}{5} \] to find k, multiply both sides by 5 \[  \frac{1}{3} \cdot 5 = \frac{k}{5}\cdot 5 \\  \frac{1}{3} \cdot 5 = k \cdot \frac{5}{5} \\  \frac{5}{3} = k \]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh i thought you said t multiply 5 into 3 , but what do you do now divide 5/3 into 10

phi
 one year ago
Best ResponseYou've already chosen the best response.1you write the formula \[ y = \frac{k}{x} \] and it might be easier to understand if you write it this way \[ y = k \cdot \frac{1}{x} \] which means the same thing. now replace k with 5/3 \[ y =  \frac{5}{3} \cdot \frac{1}{x} \]

phi
 one year ago
Best ResponseYou've already chosen the best response.1find y when x = 10. that means put in 10 for x in the formula \[ y =  \frac{5}{3} \cdot \frac{1}{x} \\ y =  \frac{5}{3} \cdot \frac{1}{10}\] and simplify

phi
 one year ago
Best ResponseYou've already chosen the best response.1if you use a calculator on \[  \frac{5}{3} \cdot \frac{1}{10} \] what do you get ?

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes, y= 1/6 when x=10. It would be good to be able to do that without the calculator. when you multiply fractions, you multiply top times top and bottom times bottom \[  \frac{5}{3} \cdot \frac{1}{10} =  \frac{5 \cdot 1 }{3 \cdot 10} \] we could multiply the bottom 3*10 to get 30 \[  \frac{5}{30} \] and then simplify to get 1/6 or, it's easier to notice that 10 is 2*5 \[  \frac{5 \cdot 1 }{3 \cdot 10} =  \frac{5 \cdot 1 }{3 \cdot 2 \cdot 5} \] and notice we have a 5 up top and down below, and they simplify to 5/5 = 1 \[  \frac{1 }{3 \cdot 2} =  \frac{1}{6} \]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0what if x=4/15 when y=105,find x when y=4

phi
 one year ago
Best ResponseYou've already chosen the best response.1\[ y = k \cdot \frac{1}{x} \\ 105= k \cdot \frac{1}{\frac{4}{15}} \]

phi
 one year ago
Best ResponseYou've already chosen the best response.1multiply both sides by 4/15,

phi
 one year ago
Best ResponseYou've already chosen the best response.1so \[y = \frac{28}{x} \] find x when y=4 replace y with y \[ 4 = \frac{28}{x} \]

phi
 one year ago
Best ResponseYou've already chosen the best response.1first multiply both sides by x then divide both sides by 4

phi
 one year ago
Best ResponseYou've already chosen the best response.1yes. \[ 4 x= \frac{28}{x} \cdot x \\ 4x = 28 \\\frac{4x}{4}= \frac{28}{4} \\x=7\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0thanks are you getting tired of me asking questions

phi
 one year ago
Best ResponseYou've already chosen the best response.1no, but I do have to go. make a new post and someone will help you.
Ask your own question
Sign UpFind more explanations on OpenStudy
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.