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
    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.
  • Question
    How to find the slope when given the graph?
    GB742
    Top Answerer
    If it's a straight line, choose any two points on the graph and use the formula m = (y2 - y1)/(x2 - x1) to find the slope. For example, if point A has the coordinates (2, 8) and point B has the coordinates (7, 15): (15 - 8)/(7 - 2) = 7/5, therefore the slope of the line which connects A and B would be 7/5.
  • Question
    How do I find the slope with only one coordinate?
    GB742
    Top Answerer
    If you only have a single coordinate, it is not possible to find the slope of the line - you need to know at least two points on the line to find the slope.
  • Question
    How do I graph when I have the slope and y-intercept and slope is a single number?
    Donagan
    Top Answerer
    Use the slope-intercept form of the equation: y = mx + b, where m is the given slope, and b is the given y-intercept. For example, if the given slope is 2, and the given y-intercept is -4, the equation will be y = 2x - 4. Then make a table of values, choosing small positive and negative values for x and calculating the corresponding values of y. Now plot the points you've found, and connect them with a line.
  • Question
    How do I find the slope of the line x - 3y - 6 = 0?
    Donagan
    Top Answerer
    First solve for y: x - 3y - 6 = 0. -3y = 6 - x. y = (x-6) / 3 = x/3 - 2. So y = (1/3)x - 2. That's in slope-intercept form, so the slope of the line is the coefficient of x, which is +1/3.
  • Question
    How do I find the slope for y = -5x - 1?
    Donagan
    Top Answerer
    This line's equation is given in the "slope-intercept" form, y = mx + b, where "m" is the slope, and "b" is the y-intercept. Therefore, the slope is given to us as -5.
  • Question
    How do I find the slope of a line (2,5) and (5,3)?
    Donagan
    Top Answerer
    The slope is (5-2)/(3-5) = 3/-2 = -3/2.
  • Question
    When doing this, the bottom is on the top of the fraction and the side is on the bottom?
    Donagan
    Top Answerer
    The vertical change (in y) is the numerator of the slope, and the horizontal change (in x) is the denominator. (If the slope is a whole number, that number can be considered the numerator, and the denominator is 1.)
  • Question
    What is the slope of y = 3x?
    Donagan
    Top Answerer
    Using the slope-intercept formula, y = mx + b, the slope (m) in this case is 3, and the y-intercept (b) is zero. (A slope of 3 means that the line moves up three times faster than it moves to the right -- or down three times faster than it moves to the left.)
  • Question
    Is there an easier way you can explain this if I don't understand it?
    Community Answer
    Choose two random points on the line. It is easiest if they are on a point where the x and y lines intersect. Pick and label which one is "point one" and "point two." Subtract y coordinate one from y coordinate two (y2 - y1) and put it as the numerator in a fraction. Do the same with the x coordinates, but put the difference as the denominator. Put the completed fraction into decimal form. A line going from left to right down will have a negative slope, and a line going up to the right will have a positive slope.
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