## Intermediate Algebra (12th Edition)

To calculate the slope between points $(x_1,y_1)$ and $(x_2,y_2)$, we use the formula: $slope=m=\frac{y_2-y_1}{x_2-x_1}$ This definition matches (D). The answer is (B) is reversed, but this yields the same result: $slope=m=\frac{y_1-y_2}{x_1-x_2}=\frac{-(y_2-y_1)}{-(x_2-x_1)}=\frac{y_2-y_1}{x_2-x_1}$ So choices (D) and (B) are correct. (A) has the subscripts mismatched, while (C) has x and y mismatched.