Question

Complete the equation of the line through (2, 1) and (5, -8).
Use exact numbers.

y = ___

Answer 1

Answer:

y = -3x + 7

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

1. Brackets
2. Parenthesis
3. Exponents
4. Multiplication
5. Division
6. Addition
7. Subtraction

• Left to Right

Algebra I

Equality Properties

Slope Formula: $\displaystyle m=\frac{y_2-y_1}{x_2-x_1}$

Slope-Intercept Form: y = mx + b

• m - slope
• b - y-intercept

Step-by-step explanation:

Step 1: Define

Point (2, 1)

Point (5, -8)

Step 2: Find slope m

Simply plug in the 2 coordinates into the slope formula to find slope m

1. Substitute [SF]:                    $\displaystyle m=\frac{-8-1}{5-2}$
2. Subtract:                              $\displaystyle m=\frac{-9}{3}$
3. Divide:                                 $\displaystyle m=-3$

Step 3: Find y-intercept b

1. Substitute in m [SIF]:                    y = -3x + b
2. Substitute in point:                       1 = -3(2) + b
3. Multiply:                                        1 = -6 + b
4. Isolate b:                                       7 = b

Step 4: Write Equation

1. Substitute in b [SIF]:                    y = -3x + 7