You can write the equation of a line given any two points on the line. First use the two given points to find the slope. Then use the slope and one of the points to write the equation.
What is an equation of the line at the right?
How does the graph help you write an equation?
You can use two points on the line to find the slope. Then use point-slope form.
Think | Write |
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You need the slope m, so start with the slope formula. |
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Use the given points to find the slope. |
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Use point-slope form. |
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Use either given point for
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✓ Got It?
Recreation The table shows the altitude of a hot-air balloon during its linear descent. What equation in slope-intercept form gives the balloon's altitude at any time? What do the slope and y-intercept represent?
How does the table help you write an equation?
The table gives four points. You can use any two of the points to find the slope. Then use point-slope form.
Time, x (s) | Altitude, y (m) |
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10 | 640 |
30 | 590 |
70 | 490 |
90 | 440 |
The slope