How do you find the y intercept?

You can take the function f(x) = something (your funtion) so like f(x)=2x. you can input x=0 and find the output which would be the y intercept. So, lets actually have f(x) = 5x + 2. You input 0 for x and you get f(x) = 2. That is your y intercept

How do you know where to put your intercepts when answering the problems.? I haven't been able to get 100% on the practice problems, because my answers need to be reversed, but I can't figure out where to place them.

in slope-intercept form, ( y=mx+b ) b represents your y-intercept.

at 0:48 where did 0 come from?

We need to find the x intercept. So, as it is a point on the x axis, the y coordinate has to be 0. So, we substitute y = 0 into the equation.

for example how would you find the x intercept for a problem like this ?Y = x2 + 5x + 4 y = x squared plus five x plus four

It's a quadratic equation, which means it's a non-linear (is parabolic in shape). You can find the x-intercepts (usually there are 2, but there can be 1 or none) by completing the square, factoring or by using the quadratic formula. Which method I use depends on which one I think will make solving the problem easier. The easiest way to solve is to factor the quadratic equation. x^2+5x+4=0 We set it equal to zero because we are looking for the x intercepts. When y is 0 where will the parabola cross the x-axis To solve by factoring we ask ourselves: What two numbers add up to the middle term and are the product of the last term? 4*1=4 (last term) 4+1=5 (middle term) (x+4) (x+1) set them both equal to zero to find the x intercept x+4=0 subtract 4 from both sides x=-4 x+1=0 subtract 1 from both sides x=-1 x intercepts are -4 and -1. Or the points where the parabola crosses the x-axis are (-4,0) and (-1,0).

Can't you find the intercept by doing -b/2a, or is that finding the vertex?

A vertex is a corner, where two lines meet. A straight line by itself doesn't have a vertex. The easiest way to find the x intercept is to figure out what value x will have when y = 0. So if you have an equation of a line: 2y + 4x = 28 you substitue "0" in for your y and solve: 2 (0) + 4x = 28 4x = 28 x = 7 The x intercept is (7,0)

Slope intercept form is y=mx+b. Is there a way to use the x-intercept instead of the y-intercept. Use p for the y-intercept in your equation. My attempt: y = mx + b 0 = mx + b 0 = x + b/m x = -b/m let p be the x-intercept therefore: p = -b/m Therefore:y = mx - mp Am I right?

If m = 3 and b = 2 (Substitute) 0 = 3x + 2 (0 = mx + b) (Subtract b from both sides) 0-2 = 3x (y-b = mx) -2 = 3x (y-b = mx) (divide both sides by the amount x is multiplied by) -2/3 = x

Theoretically could there be a "z" axis? Like on a 3 dimensional graph? Do those exist?

Yes, we could have a z-axis. You could graph planes, spheres, and all sorts of other figures. You probably won’t run into 3D graphs unless you do higher-level math. Here is an article on 3D space from the multivariable calculus course: https://www.khanacademy.org/math/multivariable-calculus/thinking-about-multivariable-function/ways-to-represent-multivariable-functions/a/multidimensional-graphs You probably won’t understand all of it yet, but you might find it interesting!

I have a question what is the equation of x intercept?

There is no equation. You take the linear equation that you have and you replace Y with 0. Then, solve for X. You will have a point on the line at (x-value, 0) where the x-value is the value you found. This point is where the line cross the x-axis (so, it is the x-intercept).

Main content

Course: 8th grade (Eureka Math/EngageNY) > Unit 4

Lesson 3: Topic C: Slope and equations of lines

x-intercept of a line

Name: x-intercept of a line
Uploaded: 2013-08-10T20:35:33Z
Description: Sal determines the x-intercept of a linear equation from a graph. Afterwards, he checks his work by plugging values back into the equation.

Google Classroom

Sal determines the x-intercept of a linear equation from a graph. Afterwards, he checks his work by plugging values back into the equation. Created by Sal Khan.

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retrest
Posted 6 years ago. Direct link to retrest's post “How do you find the y int...”
How do you find the y intercept?
Button navigates to signup pageComment on retrest's post “How do you find the y int...”
(19 votes)
Answer
- michael Li
  Posted 6 years ago. Direct link to michael Li's post “You can take the function...”
  You can take the function f(x) = something (your funtion) so like f(x)=2x. you can input x=0 and find the output which would be the y intercept. So, lets actually have f(x) = 5x + 2. You input 0 for x and you get f(x) = 2. That is your y intercept
  Comment on michael Li's post “You can take the function...”
  (23 votes)
Ani-Jay
Posted 7 years ago. Direct link to Ani-Jay's post “How do you know where to ...”
How do you know where to put your intercepts when answering the problems.? I haven't been able to get 100% on the practice problems, because my answers need to be reversed, but I can't figure out where to place them.
Button navigates to signup pageComment on Ani-Jay's post “How do you know where to ...”
(11 votes)
Answer
- bgale28
  Posted 7 months ago. Direct link to bgale28's post “in slope-intercept form, ...”
  in slope-intercept form, ( y=mx+b ) b represents your y-intercept.
  Button navigates to signup page
  (5 votes)
AshwathMalaisamy
Posted 10 years ago. Direct link to AshwathMalaisamy's post “for example how would you...”
for example how would you find the x intercept for a problem like this ?Y = x2 + 5x + 4
y = x squared plus five x plus four
Button navigates to signup pageComment on AshwathMalaisamy's post “for example how would you...”
(5 votes)
Answer
- Rachel
  Posted 10 years ago. Direct link to Rachel's post “It's a quadratic equation...”
  It's a quadratic equation, which means it's a non-linear (is parabolic in shape). You can find the x-intercepts (usually there are 2, but there can be 1 or none) by completing the square, factoring or by using the quadratic formula. Which method I use depends on which one I think will make solving the problem easier. The easiest way to solve is to factor the quadratic equation.
  x^2+5x+4=0
  
  We set it equal to zero because we are looking for the x intercepts.
  When y is 0 where will the parabola cross the x-axis
  
  To solve by factoring we ask ourselves: What two numbers add up to the middle term and are the product of the last term?
  4*1=4 (last term)
  4+1=5 (middle term)
  (x+4) (x+1)
  set them both equal to zero to find the x intercept
  x+4=0
  subtract 4 from both sides
  x=-4
  x+1=0
  subtract 1 from both sides
  x=-1
  x intercepts are -4 and -1. Or the points where the parabola crosses the x-axis are (-4,0) and (-1,0).
  Comment on Rachel's post “It's a quadratic equation...”
  (11 votes)
Sara Beth
Posted 8 years ago. Direct link to Sara Beth's post “Can't you find the interc...”
Can't you find the intercept by doing -b/2a, or is that finding the vertex?
Button navigates to signup pageComment on Sara Beth's post “Can't you find the interc...”
(5 votes)
Answer
- KathyC
  Posted 8 years ago. Direct link to KathyC's post “A vertex is a corner, whe...”
  A vertex is a corner, where two lines meet. A straight line by itself doesn't have a vertex.
  
  The easiest way to find the x intercept is to figure out what value x will have when y = 0.
  So if you have an equation of a line: 2y + 4x = 28
  you substitue "0" in for your y and solve:
  2 (0) + 4x = 28
  4x = 28
  x = 7
  The x intercept is (7,0)
  Comment on KathyC's post “A vertex is a corner, whe...”
  (8 votes)
poodoo
Posted a year ago. Direct link to poodoo's post “at 0:48 where did 0 come ...”
at
0:48
where did 0 come from?
Button navigates to signup pageButton navigates to signup page
(6 votes)
Answer
- Venkata
  Posted a year ago. Direct link to Venkata's post “We need to find the x int...”
  We need to find the x intercept. So, as it is a point on the x axis, the y coordinate has to be 0. So, we substitute y = 0 into the equation.
  Button navigates to signup page
  (4 votes)
daP0l15hc0unt
Posted 5 years ago. Direct link to daP0l15hc0unt's post “Slope intercept form is y...”
Slope intercept form is y=mx+b.
Is there a way to use the x-intercept instead of the y-intercept. Use p for the y-intercept in your equation.

My attempt:
y = mx + b
0 = mx + b
0 = x + b/m
x = -b/m
let p be the x-intercept
therefore: p = -b/m
Therefore:y = mx - mp
Am I right?
Button navigates to signup pageButton navigates to signup page
(5 votes)
Answer
- KoJesko
  Posted 5 years ago. Direct link to KoJesko's post “If m = 3 and b = 2 (Subst...”
  If m = 3 and b = 2 (Substitute) 0 = 3x + 2 (0 = mx + b) (Subtract b from both sides)
  0-2 = 3x (y-b = mx) -2 = 3x (y-b = mx) (divide both sides by the amount x is multiplied by) -2/3 = x
  Comment on KoJesko's post “If m = 3 and b = 2 (Subst...”
  (5 votes)
Ammon Trump
Posted 6 years ago. Direct link to Ammon Trump's post “How would I find the x an...”
How would I find the x and y intercepts and graph them if I have a function 3x - 5y=15
Button navigates to signup pageButton navigates to signup page
(6 votes)
Answer
- bgale28
  Posted 7 months ago. Direct link to bgale28's post “You can substitute the x ...”
  You can substitute the x or y to find the other intercept or vice versa. For example, if x was zero in 3x - 5y = 15 then your y-intercept is -3. Or for example, if y was zero in 3x - 5y = 15 then your y-intercept is 5.
  Button navigates to signup page
  (1 vote)
rreid
Posted 5 months ago. Direct link to rreid's post “i understood nothing in t...”
i understood nothing in the video
Button navigates to signup pageComment on rreid's post “i understood nothing in t...”
(5 votes)
Answer
- Angelina
  Posted a day ago. Direct link to Angelina's post “I can explain! The x-int...”
  I can explain!
  
  The x-intercept of a line is the point at which the line crosses the x-axis.
  
  In other words, it’s the value of x when y equals zero in the equation of the line.
  
  For a line represented by the equation y=mx+b,
  where m is the slope and b is the y-intercept, the x-intercept can be found by setting y to zero and solving for x.
  
  So, if we set y to zero, we get:
  
  0=mx+b
  
  Solving for x gives us:
  
  x=−b/m
  
  This value of x is the x-intercept of the line. It represents the point on the x-axis where the line intersects. If the line never crosses the x-axis, then it has no x-intercept.
  
  For example, the line
  
  y=2x+3
  
  has an x-intercept at x=−3/2
  or x=−1.5.
  
  This means the line crosses the x-axis at the point (-1.5, 0).
  
  I hope this explanation helps! Let me know if you have any other questions.
  Button navigates to signup page
  (1 vote)
Dooder
Posted 8 months ago. Direct link to Dooder's post “Theoretically could there...”
Theoretically could there be a "z" axis?
Like on a 3 dimensional graph?
Do those exist?
Button navigates to signup pageButton navigates to signup page
(3 votes)
Answer
- cameronsmith
  Posted 8 months ago. Direct link to cameronsmith's post “Yes, we could have a z-ax...”
  Yes, we could have a z-axis. You could graph planes, spheres, and all sorts of other figures. You probably won’t run into 3D graphs unless you do higher-level math. Here is an article on 3D space from the multivariable calculus course: https://www.khanacademy.org/math/multivariable-calculus/thinking-about-multivariable-function/ways-to-represent-multivariable-functions/a/multidimensional-graphs
  
  You probably won’t understand all of it yet, but you might find it interesting!
  Button navigates to signup page
  (3 votes)
Nakulisthebest
Posted 2 years ago. Direct link to Nakulisthebest's post “I have a question what is...”
I have a question what is the equation of x intercept?
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(3 votes)
Answer
- Kim Seidel
  Posted 2 years ago. Direct link to Kim Seidel's post “There is no equation. Yo...”
  There is no equation. You take the linear equation that you have and you replace Y with 0. Then, solve for X. You will have a point on the line at (x-value, 0) where the x-value is the value you found. This point is where the line cross the x-axis (so, it is the x-intercept).
  Button navigates to signup page
  (2 votes)

Video transcript

The graph of the line 2y plus 3x equals 7 is given right over here. Determine its x-intercept. The x-intercept is the x value when y is equal to 0, or it's the x value where our graph actually intersects the x-axis. Notice right over here our y value is exactly 0. We're sitting on the x-axis. So let's think about what this x value must be. Well, just trying to eyeball a little bit, it's a little over 2. It's between 2 and 3. It looks like it's less than 2 and 1/2. But we don't know the exact value. So let's go turn to the equation to figure out the exact value. We essentially have to figure out what x value, when y is equal to 0, will have this equation be true. So we could just say 2 times 0 plus 3x is equal to 7. Well, 2 times 0 is just going to be 0, so we have 3x is equal to 7. Then we can divide both sides by 3 to solve for x, and we get x is equal to 7/3. Does that look like 7/3? Well, we just have to remind ourselves that 7/3 is the same thing as 6/3 plus 1/3. And 6/3 is 2. So this is the same thing as 2 and 1/3. Another way you could think about it is 3 goes into 7 two times, and then you have a remainder of 1. So you've still got to divide that 1 by 3. It's 2 full times and then a 1/3, so this looks like 2 and 1/3. And so that's its x-intercept, 7/3. If I was doing this on the exercise on Khan Academy, it's always a little easier to type in the improper fraction, so I would put in 7/3.