Final answer:
To write an equation of a line in slope-intercept form with a given slope and point, substitute the values into the formula y = mx + b.
Step-by-step explanation:
To write an equation of a line in slope-intercept form, use the formula y = mx + b, where m is the slope of the line and b is the y-intercept. Given that the slope is -3 and the line crosses through the point (3,-1), substitute the values into the formula.
Using the point-slope form, we can determine that y - y1 = m(x - x1). Plugging in the values into this form, we get y - (-1) = -3(x - 3). Simplifying the equation gives y + 1 = -3x + 9. Now, we rearrange the equation to slope-intercept form by isolating y.
The final equation in slope-intercept form is y = -3x + 8.
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