Point-Slope Form Calculator
Use a slope and one known point to find y at another x and the intercept b in y = mx + b.
Formula
y − y₁ = m(x − x₁); y = y₁ + m(x − x₁); b = y₁ − mx₁.
Calculated y ≈ (3)+(2)×((4)-(1)) · y-intercept b ≈ (3)-(2)×(1)
How to use
- Enter the slope m.
- Enter the known point (x₁, y₁) and the target x.
- Read y and b; the line is y = mx + b.
Examples
- For m=2 and (1,3), the line is y=2x+1; at x=4, y=9.
Frequently asked questions
Can the slope be negative?
Yes. A negative m describes a line that falls as x increases.
What about a vertical line?
Its slope is undefined, so this form cannot represent it.
Which coordinates are known?
x₁ and y₁ belong to one point; x is the new coordinate where y is calculated.
Sources
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