Using the Slope Formula

1.12.1 Using the Slope Formula

1.12.1 • Using the Slope Formula

Warm Up

Use the slope formula, m=y2−y1x2−x1m=y2−y1x2−x1, to find the slope of the line through the given points.

1.

(1,−2)(1,−2) and (3,4)(3,4)

Compare your answer:

m=3m=3

First, name (1,−2)(1,−2) as point 1 and (3,4)(3,4) as point 2.

(x1,y1)(x1,y1) and (x2,y2)(x2,y2)

(1,−2)(1,−2) and (3,4)(3,4)

Use the slope formula.

m=y2−y1x2−x1m=y2−y1x2−x1

Substitute the values: y2=4,y1=−2,x2=3,x1=1y2=4,y1=−2,x2=3,x1=1.

m=4−(−2)3−(1)m=4−(−2)3−(1)

Simplify.

m=62m=62

m=3m=3

2.

(−2,−3)(−2,−3) and (−7,4)(−7,4)

Compare your answer:

m=−75m=−75

First, name (−2,−3)(−2,−3) as point 1 and (−7,4)(−7,4) as point 2.

(x1,y1)(x1,y1) and (x2,y2)(x2,y2)

(−2,−3)(−2,−3) and (−7,4)(−7,4)

Use the slope formula.

m=y2−y1x2−x1m=y2−y1x2−x1

Substitute the values: y2=4,y1=−3,x2=−7,x1=−2y2=4,y1=−3,x2=−7,x1=−2.

m=4−(−3)−7−(−2)m=4−(−3)−7−(−2)

Simplify.

m=7−5m=7−5

m=−75m=−75