Q&A for How to Find the Slope of a Line

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  • Question
    How do I find slope of 2x - 4y = 20?
    Donagan
    Top Answerer
    Re-work the equation until y is isolated on one side. Then note the coefficient of the x term. That's the slope. In this example, we re-work the equation until we isolate y: y = x/2 - 5. The coefficient of x is ½, so the slope of the line is ½.
  • Question
    How do I find the slope of a line y=9?
    Community Answer
    For all lines where y equals a constant and there is no x, the slope is 0.
  • Question
    How do I use a protractor and trigonometry to find slope of a line?
    Donagan
    Top Answerer
    The slope of a line is a non-angular representation of the angle between the line and a horizontal line such as the x-axis. Use a protractor to measure that angle, and then convert the angle to a decimal or a fraction using a trig table. For example, if a protractor tells you that there is a 45° angle between the line and a horizontal line, a trig table will tell you that the tangent of 45° is 1, which is the line's slope. Most angles do not have such a simple tangent. For instance, a 30° angle has a tangent of 0.577. You could use that as the slope, or you could convert the decimal to a fraction, but in this case it would be a rather unwieldy fraction (577/1000 or 72/125).
  • Question
    How do I find the slope of a function with 3 nonlinear points?
    Donagan
    Top Answerer
    You're describing a curved line. Each point on a curve has its own unique slope, so the curve (or function) as a whole does not have a specific slope.
  • Question
    How do I find the slope when x is 5 and -6, and y is -5 and -4?
    Donagan
    Top Answerer
    The slope is the change in y divided by the change in x. The change in y is (-4) - (-5) = -4 + 5 = +1. The change in x is (-6) - (+5) = -6 - 5 = -11. So the slope is +1 / -11 = -1/11. (A negative slope means the line moves down as it moves from left to right, and this slope is just slightly negative.)
  • Question
    Does it matter which two points I choose?
    Community Answer
    No. Since the line increases at a constant rate, the ratio of (y2-y1)/(x2-x1) will stay the same.
  • Question
    How can I find the slope of the line passing through the points -7, 8 and 5, -7?
    Community Answer
    Answer is -5/4. You take 8 as your y2 and -7 as your x2. With the rest following in that order, you will be able to get -15/12 which is equal to -5/4.
  • Question
    How do I find a slope with no points?
    Donagan
    Top Answerer
    You would have to use a protractor and trigonometry.
  • Question
    Can I find the slope of -1?
    Donagan
    Top Answerer
    A straight line with a slope of -1 moves down at a 45° angle as it moves to the right.
  • Question
    How to find a slope of a line when equation of a line is given?
    Community Answer
    When you are given a slope-intercept form equation, then finding the slope is simple: since the slope-intercept form is y = mx + b, and m = slope, it would simply be the coefficient of x. For example, if the question were, "Find the slope when the equation is y = 5x + 2", the slope would be 5, because that is where the slope goes in a slope-intercept form.
  • Question
    How do I find the slope of a line when the line doesn't line up to (0,0)?
    Donagan
    Top Answerer
    The method shown above works with any straight line on a coordinate plane. The line does not have to pass through any particular point. Note that the line in the images above does not pass through (0,0).
  • Question
    Does it have to be simplified when I get an answer like 7.5/6?
    Donagan
    Top Answerer
    It's usually best to simplify any answer. In this case the slope is 1.25 or 1¼. (An unsimplified fraction such as 5/4 is also an acceptable answer when you're dealing with slope.)
  • Question
    How do I find slope without a graph?
    Donagan
    Top Answerer
    Presumably you would have an equation representing the line. If the equation is not already expressed in the form "y = mx + b", arrange it in that form. m will be the slope. (This is for straight-line graphs only.)
  • Question
    Is slope the same thing as gradient?
    Community Answer
    Yes, "slope" is also referred to as "gradient."
  • Question
    What is the slope between (0,5) and (3,8)?
    Community Answer
    We'll designate 8 as y2 and 3 as x2. Then 5 is y1 and 0 is x1. So the slope is (8 - 5) / (3 - 0) = 3/3 = 1.
  • Question
    What is the slope of 2x - 4y = 20?
    I_l1ke_gam3s
    Community Answer
    Isolate y. Subtract 2x on both sides. -4y = -2x + 20. (y = mx + b form). Then divide by -4 on both sides. y = 1/2x - 5. The number in front of the x is 1/2, so that's your slope.
  • Question
    How do I find the slope of +3x and -2y?
    I_l1ke_gam3s
    Community Answer
    The slope is going to be -3/2. The equation will be -2y = 3x + b, so y = -3/2x + b/2. We don't know what b is, but it doesn't matter.
  • Question
    How do I find the slope?
    I_l1ke_gam3s
    Community Answer
    Isolate y in the equation. Just make sure the equation is in y = mx + b form for this. The unit inside the "m" portion is your slope.
  • Question
    How do I find the slope of y=15?
    I_l1ke_gam3s
    Community Answer
    When the y value is just a constant, that number becomes a point. It has no run and no rise. As in this case when the y equals a constant, the slope is equal to zero. So the slope is 0.
  • Question
    How do I look for the equation of a line?
    I_l1ke_gam3s
    Community Answer
    See the wikiHow article How to Find the Equation of a Line for further information.
  • Question
    How do I find the slope of the line 2x+5y=-2?
    I_l1ke_gam3s
    Community Answer
    Subtract 2x on both sides. 5y = -2x + 2. Then divide by 5 on both sides. y = -2/5x + 2/5. This is in y = mx + b form where m is the slope. Therefore, your slope, m, is -2/5.
  • Question
    What is the slope of the line connecting (4,2) and (6,1)?
    Community Answer
    The slope is (y2 - y1) / (x2 - x1). (1 - 2) / (6 - 4) = -1 / 2.
  • Question
    What does m mean in the slope-intercept equation?
    Community Answer
    m is the slope of the line. The slope is the amount of change in the y-value of the line as its x-value changes.
  • Question
    If one of my numbers is negative, do I change the subtraction sign to positive when using the formula y2-y1/x2-x1?
    Community Answer
    Subtracting a negative number is the same as adding a positive number. For example, if y2 is 4, and y1 is -2, when you subtract y1 from y2, you get 4 - (-2) = 4 + 2 = 6. Another example: if y2 is -5, and y1 is -3, when you subtract y1 from y2, you get -5 - (-3) = -5 + 3 = -2. In each case, you are looking for the "distance" between y2 and y1 or between x2 and x1. For example, the "distance" (number of units on a number line) between +1 and -5 is 1 - (-5) = 1 + 5 = 6.
  • Question
    What is the slope of the line -x - 4y = 12?
    Community Answer
    First change the equation into the standard form (y = mx + b), where m is the slope. Thus, we solve for y. Do this by adding x to both sides (so that -4y = x + 12) and then dividing both sides by (-4): that gives you y = -x/4 - 3. Now that the equation is in standard form, we can see that "m" (the coefficient of x) is -1/4. That's the slope.
  • Question
    How do I write an equation in slope-intercept form?
    Community Answer
    First recognize that the slope-intercept form applies only to linear (straight-line) equations, those that have no exponents other than 1. Manipulate the equation until it takes the form of y = mx + b. For example, if the equation is 4x + 2y = 8, you would subtract 4x from both sides of the equation and then divide both sides by 2. That results in the equation y = -4x + 8. That's the slope-intercept form. Be aware that both m and b can be either positive or negative, and they can be whole numbers or fractions.
  • Question
    How do I find the slope of y = 3x - 2?
    I_l1ke_gam3s
    Community Answer
    The slope is 3. This is in y = mx + b form. m is the slope and b (-2) is the y-intercept.
  • Question
    Is y=mx+b the slope formula, or is it m=(y2-y1)/(x2-x1), or is it y-y1=m(x-x1)
    I_l1ke_gam3s
    Community Answer
    y = mx + b is the "slope-intercept form". m = y2-y1/x2-x1 is one way to find the slope when you're given two points. y - y1 = m(x-x1) is known as the "point-slope form".
  • Question
    How do I find the slope of 4x=7y+5?
    I_l1ke_gam3s
    Community Answer
    Solve for y. First subtract 5 from both sides: 4x - 5 = 7y. Then divide both sides by 7: y = 4/7x - 5/7 = y. The number in front of x is 4/7, so that's the slope.
  • Question
    How do I find the slope for (6,10) and (6,-2)?
    Community Answer
    Because those two points have the same x-coordinate, the line is vertical (parallel to the y-axis). That makes the slope infinite or undefined, so it cannot be stated.
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