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Slope-Intercept Form Calculator

Find slope-intercept form y = mx + b from two points.

Reviewed for accuracy by the Math Ora X team Last updated

Result

About Slope-Intercept Form Calculator

Slope-intercept form: y = mx + b where m is slope and b is y-intercept. Standard form: Ax + By = C.

$$y = mx + b$$

How to use this calculator

  1. Enter the two points into the calculator.
  2. Use the points to find the slope.
  3. Use one point and the slope to solve for the y-intercept.
  4. Write the final equation in slope-intercept form.

The formula explained

$$ m = \frac{y_2 - y_1}{x_2 - x_1}, \text{ then } y = mx + b, \text{ so } b = y_1 - mx_1 $$

  • \(m\) = slope
  • \(b\) = y-intercept
  • \(x_1, y_1\) = the first point
  • \(x_2, y_2\) = the second point
  • \(x, y\) = coordinates on the line

Step by step method

  1. Start with two points, such as \((1, 3)\) and \((5, 11)\).
  2. Find the slope by subtracting the y-values and dividing by the difference in x-values.
  3. Substitute the slope and one point into \(y = mx + b\) to find \(b\).
  4. Write the equation as \(y = mx + b\).

Worked example

Suppose you want the line that passes through the points (2, 5) and (6, 13).

  1. Find the slope: \(m = \frac{13 - 5}{6 - 2} = \frac{8}{4} = 2\).
  2. Use one point, such as \((2, 5)\), in \(y = mx + b\): \(5 = 2(2) + b\).
  3. Solve for \(b\): \(5 = 4 + b\), so \(b = 1\).
  4. Write the equation: \(y = 2x + 1\).

Answer. y = 2x + 1

Tips and common mistakes

  • Make sure the two points are not the same point, or the slope cannot be found.
  • Keep the x-values paired with the correct y-values from each point.
  • Watch the signs carefully when subtracting coordinates.
  • If the line is vertical, slope-intercept form does not apply.

Frequently asked questions

What if the two points have the same x-value?+

That makes a vertical line. Vertical lines do not have a slope-intercept form because the slope is not defined. The calculator can only give slope-intercept form when the line is not vertical.

Do I need to simplify the fraction for slope?+

Yes, if the slope comes out as a fraction, it should be reduced when possible. A simplified slope makes the final equation cleaner and easier to read. The calculator should show the simplest correct form.

Can I use negative coordinates?+

Yes, negative coordinates work normally. Just be careful with subtraction, especially when a negative number is involved. Sign mistakes are the most common source of errors.

Why does the calculator use one point after finding the slope?+

Once the slope is known, one point is enough to find the y-intercept. The line is fully determined by its slope and intercept. Using either point should lead to the same final equation.

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