Introduction to Linear Demand Equations

A simple equation can be used to express the relationship between the price of a good and the demand among that good’s consumers. This lesson will examine the different variables included in the typical equation for demand, expressed as Qd = a – bP.

We will use a simple equation for demand to plot a demand schedule and a demand curve for pizzas.

Once you’ve watched this video, see if you can complete the following Khan Academy excercises:

After watching the video complete Part 1 of the practice activity 1.1 Linear Demand and Supply Equations

Linear Demand Equations – Part 1

In-class activity: Use the linear demand function for cappuccinos, Qd = 500 – 25P to answer the questions that follow:

  1. Create a demand schedule for cappuccinos with the prices of $0, $1, $3, $5, $7 and $9
  2. Create a demand curve for cappuccinos, plotting the points from your demand schedule.
  3. Assume the price of latte machiatos, a close substitute for cappuccinos, decreases, and causes the a variable in the demand function to fall to 300. Create a new demand schedule, with the adjusted values for Qd.
  4. On your previous diagram, illustrate the new demand curve.
  5. Assume that due to falling incomes, cappuccino consumers become more sensitive to changes in the price of cappuccinos, and the variable in the original demand function increases to 40. Using the same prices, create a new demand schedule.
  6. On the same graph as your original demand curve, illustrate the new demand for cappuccinos following the decline in consumers’ incomes.


4 Responses

  1. Pingback: Linear Demand Equations – Shifts in Demand | The Economics Classroom

  2. Sudha Jatwani says:

    Hi Jason,

    Thanks for the videos. They are really insightful. I have a few doubts though. Requesting you to clarify.

    I am unable to understand why is there a demand at price zero and why is there a change in demand from 800 to 600 when there is a fall in the price of hamburger? At price zero how can the demand for pizza fall?
    Finally can you also let me know the reason why demand curve is touching the X axis? According to me, the demand for any product should be free floating in case the price is zero.

    Requesting you to clarify as soon as you can.

    Thanks & Best Regards,


    • Jason Welker says:

      Sudha Jatwani » Hi Sudha, let me respond to your questions below:

      1) Why is there a demand at price zero and why is there a change in demand from 800 to 600 when there is a fall in the price of hamburger?
      The reason demand for pizzas decreases from 800 to 600 is that hamburgers are a substitute good, therefore consumers will demand fewer pizzas at every price when hamburgers become cheaper. The decrease from 800 to 600 signifies an inward shift of the demand curve, meaning demand for pizzas decreases when hamburgers become cheaper. The demand for pizza will fall at the price of zero and at all other possible prices greater than zero, since even when pizza is free fewer people will want to consume it if hamburgers are cheaper.

      2) can you also let me know the reason why demand curve is touching the X axis?
      Of course, in most real markets the demand quantity of a good demanded will increase at and increasing rate as the price approaches zero, so demand would therefore flatten out as rational consumers would likely demand ever increasing quantities as price approaches zero. In our case, however, we study LINEAR demand equations. This is a very simple model of demand, and since every demand curve is a straight line, it must intersect the x-axis (which we call the quantity axis) at some point. The point of intersection is understood as the “autonomous level of demand” , or the quantity that would be demanded when price is zero. Presumably, there is a maximum amount of a product that consumers would demand even if it were free. In the case of pizzas, we can assume that the market above represents a small town with a few thousand people in it, and the demand above represents the demand in a certain period of time (let’s say one week). So, if pizza was free, this town will consume no more than 800 pizzas in a week. That is not an unreasonable assumption. If it were the WORLD demand for pizzas and there were billions of consumers, of course the demand would be greater. Or if we extended the time period to one month or one year, then the Q-intercept would be greater.

      I hope this answers your questions! Best of luck!

  3. Pingback: Video Lectures – Linear Supply Equations | Economics in Plain English

Leave a Reply

  • hot college girl seduces soldiers fuck
  • Ugly teen nude
  • Hardcore xxx sex movies
  • big black booty and sexy toes
  • young fresh fuck free mpeg
  • wife having sex pics
  • Perfect sexy ebony teen ass
  • ebony pictures naked
  • couple swinger vids
  • teen girls with older man sex
  • korean song lyrics boy girl
  • pussy upskirt flash
  • young teen ashlie
  • Ass sex movies
  • teen with curves fuck
  • teen bikini loose top
  • girls fingering sleeping girls
  • shilpa shetty nude photo
  • hardcore leasbian
  • adult small girls breasts
  • oma old pussy
  • asian lesbian video free
  • dick suck black
  • gallery amateur string
  • naked indian girls and amateur
  • petit teen sex vids
  • hot asian girls photos
  • sexy young boy and girl alone
  • free teen orgasm vids
  • amateur coiples videos
  • black teen anal fisting
  • Gallery hardcore picture sex teenage
  • viet anal fuck
  • lesbian mom daughter movie
  • long free interracial movies
  • Sexy tamil girls photos
  • japanese teen blowjob vids
  • friend cums in my wife video
  • sex swingers for bi sex
  • young nubile sex pics
  • Fake sex photos
  • shemale sex hardcore photo gallery free
  • naked pussy chi chi
  • free young tight sex
  • erotic schoolgirl stories lactation
  • mature women seducing younger women
  • weird fat pussy
  • Anal fisting slut
  • old indian man fucks young girl
  • womens petite xxl dresses
  • young girls sucking coks
  • xxx dig dick deap throat
  • ebony lesbian bukake
  • free skinny anal
  • girl bondage sex videos
  • mature moms and daughters videos
  • naked free post pictures
  • totally fre video
  • teen anal hennesey
  • Rihanna nude pics leak
  • shy cute teen full video fuck
  • booty anal sex movie
  • threesome sex video
  • lesbian single girl
  • black pussy express
  • rubber hardcore sex movies
  • swinger wife movies
  • free movies with sex
  • forced to suck cock galleries
  • asian girls getting pussies fingered
  • home made softcore movie
  • japan girl train grope molest video
  • Nude chicks video
  • very young aacup nude picture
  • xxx teen pictures
  • young sexy girls models
  • cupples looking for girls sex
  • fre teen ebony
  • free teen pussy booty ass pics
  • giant pussy shaved
  • free bbw video
  • womens petite x cotton sweats
  • Sex and sexy girls
  • Goth girl fucking
  • Adrianne barbeau nude pics
  • hot french teen fuck
  • blonde babes video
  • sex stories black men
  • mature nudes and sex
  • young ebony teens x tubes
  • black girls pink area
  • princess teen girls diapers
  • quivira petite syrah
  • shemal fuck pussy
  • hot girl stripping naked
  • young gag
  • britney spears new video topless
  • little girl d sex
  • wife loves sex wirh birg sexs
  • british sex movie free full length
  • bitch screams loud pussy
  • teen getting anal fisted
  • amateur anal sex video free
  • couples webcam jobs
  • belly dancing sexy tits
  • Sex teen vids
  • Student sex
  • i fuck my mommy videos
  • hot wife black man
  • Beautiful teens fuck
  • free young teenie vids
  • Naked girls home
  • co ed lesbian sex videos previes
  • Girls milking boobs
  • amateur video mature hirsute
  • Redhead nude photos
  • twlight sex video
  • strap on chicks videos
  • glamour models black cock
  • tall petite naked girls
  • adult amateur videos sex
  • young asain sexy dance
  • kitty lea pussy
  • Teens fucking huge cocks
  • sexy blond fuck
  • adeanna cooke naked videos
  • anal stories
  • extremely hot lesbian girls
  • big wet butts xxx
  • hot black chick video
  • tiny tits girlie
  • hoot girls tits
  • pool party albums bikini
  • free handjob movie collection
  • naked schoolgirls video
  • black dick and white women stories
  • free amateur drunk girlfriend
  • black on live webcam
  • Julia roberts sex movies
  • yoga sex video
  • home video cum facial
  • hollywood video black friday sale
  • teen kasia photos and galleries
  • elite teen pics
  • suck it xxx
  • free self suck vids
  • Sexy ass girls in thongs
  • younger ass sites
  • girl wrestle videos
  • ghost sex with sleeping girl
  • Nude lesbian vids
  • snorg girl naked
  • pussy willow buds branch spray decorations
  • streaming video free lesbian
  • japan grand prix adult movie
  • sex machines vids
  • mature big boob vids
  • sexy naked women tits hot
  • young men hard cocks lick pussy
  • teen star magazine pics
  • boobs and a hot girl
  • Lesbian sex sexy kiss
  • hardcore hien video
  • chelsea can suck a united dick
  • hardcore granny sex
  • Sister sex images
  • what to test anal sex with
  • girls skirt party
  • amateur downblouse video
  • danger facial triangle picture
  • free long mature sexy
  • xxx hardcore virgins
  • electronic pussy stimulation
  • yee teen so so young
  • free amateur long sex movies
  • Young nude images
  • amateur xxx thumbs free
  • gorgeous bikini fuck video
  • teen sex group pics
  • black boobs movies
  • pictures of dripping pussy
  • easiest anal sex position
  • blackstripper fuck the bride to be
  • chubby black shemale mpegs
  • california babes movies
  • free naked black men videos
  • ludicris pussy poppin
  • free lesbiab
  • cock sex blonde ass
  • best homemade fuck videos
  • asian abused by doctor video
  • Jessica lynn big tits in sports
  • Girl getting fucked hardcore
  • Sex beach pictures
  • forced fuck movie videos
  • lb girls sexy skinny
  • Her fist lesbian sex
  • naked girl live webcam
  • How to approach a girl for sex
  • homemade mature wife sex
  • naked picture of asafa powell
  • teen girls bikini gallery
  • free teen babe galleries
  • young japanese blowjob
  • hentia girls with dicks
  • girl gets drilled in the ass
  • asian picure archives
  • susie sparks spreading her pussy
  • real young amateur thumbs
  • pussy thong fucked
  • mature woman with lads free movies
  • i like fucking black teens
  • vibrator in pussy and ass
  • hard fuck site
  • exhibition couple amateur photo video
  • japanese erotic tubes
  • softcore beach video
  • free albino girl movie
  • asian tragedy movies
  • fantasy cougar teen boy blowjob
  • facial cum gallery
  • american teen xxx video
  • girls moaning and screaming during sex
  • petite teen hardcore
  • redhead muscle girls nude pics
  • Nude teenage female beachgoers
  • wet pussy girlfriend
  • asian teen kyoto hardcore
  • army women sex pics
  • kagome and inuyasha sex pictures
  • busty mature strap on lesbian tube
  • hardcore movies
  • ladies kissing girls pussy
  • frre home fuck movies
  • skinny girl cuming video
  • granny mature xxx freepics
  • weirdest thing put in pussy
  • nude models pussy
  • xvideo dark chocolate pussy
  • blonde sexy women
  • free ebony couples
  • Asian pussy lesbian
  • Hot babs girls
  • big booty sex vids
  • teen erotic milf
  • Pretty indian girls
  • interracial jizz videos
  • free japan av models video
  • mature black woman in tube
  • shemale fuck girl free xxx
  • japanese girl squid xxx
  • grade school upskirt pussy
  • xxx young ass teen free videos
  • erotic confessions movie
  • Girl public sex
  • video girls fucking a bottle
  • wife fucked in the ass videos
  • love younger girls
  • hottest redhead anal sex
  • Young ass videos
  • young hot teen girls fucked hard
  • dare wife pictures
  • free videos of sleeping sex
  • wife strip for husband video
  • girl sling bikini
  • hot young teen sex
  • young black girls stripping
  • hot cartoon girls xxx
  • girls that pay you for sex
  • hardcore star fucked
  • things teenage girls say
  • young old interracial
  • celebirty videos
  • asian hardcore anal pussy
  • sexy cartoons girls
  • bree olsen pussy
  • couple filmed in public oral sex
  • black man for my wife
  • girls pedal pumping videos
  • female ebony muscle stars
  • free naked teen girl galleries
  • amateur anal babe
  • free amateur women pics
  • Wow nude patch pictures
  • sexy women naked and having sex
  • teen girls online sex webcam
  • Ebony teen booty