Math Problem Statement

find an equation in slope-intercept form for the line that passes through the points (-3,-1) and (5,5)

Solution

To find the equation of a line in slope-intercept form y=mx+by = mx + b, we need the slope mm and the y-intercept bb.

Step 1: Find the slope mm

The formula for the slope between two points (x1,y1)(x_1, y_1) and (x2,y2)(x_2, y_2) is: m=y2y1x2x1m = \frac{y_2 - y_1}{x_2 - x_1} Substitute the points (3,1)(-3, -1) and (5,5)(5, 5): m=5(1)5(3)=5+15+3=68=34m = \frac{5 - (-1)}{5 - (-3)} = \frac{5 + 1}{5 + 3} = \frac{6}{8} = \frac{3}{4}

Step 2: Use point-slope form to find bb

Now that we know the slope is m=34m = \frac{3}{4}, use one of the points to find the y-intercept bb. Let's use (5,5)(5, 5).

Substitute the point (5,5)(5, 5) into the equation y=mx+by = mx + b: 5=34(5)+b5 = \frac{3}{4}(5) + b Simplify: 5=154+b5 = \frac{15}{4} + b To solve for bb, subtract 154\frac{15}{4} from both sides: 5154=b5 - \frac{15}{4} = b Convert 55 to a fraction with denominator 4: 204154=b\frac{20}{4} - \frac{15}{4} = b Simplify: b=54b = \frac{5}{4}

Step 3: Write the equation

Now that we know m=34m = \frac{3}{4} and b=54b = \frac{5}{4}, the equation of the line is: y=34x+54y = \frac{3}{4}x + \frac{5}{4}

Would you like further details or clarifications? Here are 5 related questions to explore this topic:

  1. How do you convert slope-intercept form to standard form?
  2. What is the significance of the slope in real-life applications?
  3. How do you find the slope if the line is vertical or horizontal?
  4. Can you calculate the equation of a line parallel to the one we just found?
  5. How would you find the equation of a perpendicular line?

Tip: Always double-check your slope calculation, as small sign errors can lead to incorrect answers.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Equations
Slope-Intercept Form

Formulas

Slope formula: m = (y2 - y1) / (x2 - x1)
Slope-intercept form: y = mx + b

Theorems

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Suitable Grade Level

Grades 8-10