Main content
6th grade
Unit 7: Lesson 7
Intro to inequalities with variables- Testing solutions to inequalities
- Testing solutions to inequalities (basic)
- Plotting inequalities
- Plotting an inequality example
- Graphing basic inequalities
- Inequality from graph
- Plotting inequalities
- Inequalities word problems
- Inequalities word problems
- Graphing inequalities review
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Inequalities word problems
Learn how to write inequalities to model real-world situations.
Want to join the conversation?
- How about if you have a problem like this? :
Describe the numbers x and y such that if x>y, then x^2=y^2
I tried to write an equation like this:
x>y=y^2
This is as close as I have gotten so far. If someone could explain the procedures to do this problem, that would be greatly appreciated! Thank you! :)(15 votes)- x=-y should be the answer. For example, if x is 2 and y is -2, x^2=y^2=4. Hope this helps.(0 votes)
- can the variable be on either side and if not how does that change it?(16 votes)
- The variable can start out on one or both sides. When you finish solving, the variable will be on one side. It does not matter which side. For example: x>3 is the same as 3<x
Hope this helps.(8 votes)
- - The speed of sound is approximately 768 miles per hour. When an object travels faster than the speed of sound, it creates a sonic boom. And there's actually a whole video on how sonic booms are created, on Khan Academy. I encourage you to watch it, it is actually fascinating. But anyway, back to this question. Write an inequality to represent, s, the speeds at which a moving object creates a sonic boom. So we'll start an inequality, we'll do what they told us to. S, let's see. S has to be, they say when an object travels faster than the speed of sound. So our speed has to be greater than the speed of sound. Our speed has to be greater than the speed of sound, which is 768 miles per hour, so s has to be set greater than 768. Now another way we could have written that is that 768 needs to be less than s. We could have written 768 needs to be less than s. That's another way we could write it. In either case, our speed is going to be greater than 768 miles per hour. We check our answer. Let's do a few more of these. To cook a steak to medium-rare, it needs to have an internal temperature of 135 degrees Fahrenheit. A lower internal temperature will undercook the steak. Write an inequality to represent all of the possible temperatures, t, of an undercooked steak. Well, to be an undercooked steak your temperature is going to be less than 135 degrees. So your temperature, t, is going to be less than. You could either just use the less than on your keyboard, or you could click over here on less than. Your temperature is going to be less than 135. We're assuming your temperature is in Fahrenheit degrees. So your temperature needs to be less than Fahrenheit, less then 135 degrees, if you are going to have an undercooked steak. So, you got that one right. Let's do a couple more. Or one, let's do one more. Simone is going snowboarding tomorrow if the temperature is equal to or colder than five degrees celsius. Write an inequality to represent the temperatures at which Simone will go snowboarding. So you might want to say "Oh, well "maybe you know that t is less than five degrees." Remember, they're telling us that the temperature is equal to or colder, so she's even willing to go snowboarding if it's less than or equal to five degrees. So instead of just saying less than, let's say less than or, whoops. Let's say less than or equal to five degrees. So this inequality represented here, this shows us all of the temperatures at which she is willing to go snowboarding. We check our answer and we got it right.(9 votes)
- He didn’t type that… did he?(11 votes)
- 60 + 9 = 69 right?(9 votes)
- I dont know how to do the inequality test it is hard for me I cant do the plotting nor the graphic(5 votes)
- What are ways to check inequalites(4 votes)
- Can you explain what you mean by "Checking" inequalities? Do you want to compare them?(2 votes)
- is 4 + 20 420?(4 votes)
- easy i just thought that o was weird(4 votes)
- Why is this so hard?(4 votes)
- The temperature every day for a week was above 70 degrees. Write an inequality for the situation, use x as the variable.(3 votes)
Video transcript
- [Instructor] We're told that Eric is shorter than Priti. Priti is 158 centimeters tall. Write an inequality that
compares Eric's height in centimeters, E, to Priti's height. Pause this video and
see if you can do that. Alright, so we have Eric's height, which we are using the
variable capital E for, And how does it compare? It says Eric is shorter than Priti. So Eric's height is going to be less than whatever Priti's height is,
which is 158 centimeters. You could think about
it on a number line too. If I were to draw a number line like this, and this is 158
centimeters, Priti's height, Eric's is gonna be less than
that 'cause he is shorter. So it would be all of the
values that are to the left of, let me do this in another color, that are less than that. Just like that. Let's do another example. Here we are told that Sydney wears skirts when the temperature is warmer
than 25 degrees Celsius. Write an inequality that describes T, the temperatures at which
Sydney wears skirts. So again, pause this video and see if you can have a go at that. Alright. So when does Sydney wear skirts? When the temperature is warmer
than 25 degrees Celsius. Now, warmer means that
the temperature is higher than 25 degrees Celsius, or that the temperature is
greater than 25 degrees Celsius. And we're using capital
T to denote temperature. So we would say capital
T, this needs to be higher than 25 degrees, or greater
than 25 degrees Celsius. So T is greater than 25. Let's do one last example here. So here we are told that Lola
and Hayley are running a race. Lola finishes the race in 53 seconds. Hayley finishes after Lola. Write an inequality that represents H, Hayley's finish time in seconds. Pause the video and see if
you can think about this. Alright, so how does
Hayley compare to Lola? Hayley finishes after Lola. So what does that mean
about Hayley's time? Well, that means that Hayley
is going to take more time than Lola to finish the race. So whatever Lola's time is, Hayley's time is going to be longer,
or more, or greater than. So Hayley's time is going to
be greater than Lola's time, which is 53 seconds, because Hayley finishes after.