body{margin:0;} noscript{z-index: 10000; position: fixed; display: block; height: 100%; width: 100%; background: #fff;} noscript .fa{font-size: 40px; display:block; color: #daa520;} noscript div{margin-top: 6%; padding-left: 20px; padding-right: 20px; text-align: center;} ! You must have JavaScript enabled to use this site.

Pearson Algebra 1 Common Core, 2011

PA

Pearson Algebra 1 Common Core, 2011 View details

3. Slope-Intercept Form

Continue to next subchapter

Exercise 29 Page 312

Start by using the Slope Formula to find the slope.

y=- x+2

Practice makes perfect

Let's start by recalling the slope-intercept form of a line. y= mx+b Here, m is the slope and b is the y-intercept. We will use the two given points to calculate these values. Let's find the slope m by substituting the points into the Slope Formula.

m=y_2-y_1/x_2-x_1

SubstitutePoints

Substitute ( - 2,4) & ( 3,- 1)

m=- 1- 4/3-( - 2)

▼

Simplify right-hand side

a-(- b)=a+b

m=- 1-4/3+2

Add and subtract terms

m=- 5/5

MoveNegNumToFrac

Put minus sign in front of fraction

m=-5/5

a/a=1

m=- 1

Now that we know that the slope is - 1, we can write a partial equation of the line. y= - 1 x +b ⇔ y=- x+b To complete the equation, we need to determine the y-intercept b. Since we know that the given points satisfy the equation, we can substitute one of them and solve for b. Let's use ( - 2, 4).

y=- x+b

x= - 2, y= 4

4=-( - 2)+b

▼

Solve for b

- (- a)=a

4=2+b

LHS-2=RHS-2

2=b

Rearrange equation

b=2

We know that the value of the y-intercept is 2. We can now complete the equation. y=- x+2

Subchapter links

Lesson Check p.311

Practice and Problem-Solving Exercises p.312-314

Standardized Test Prep p.314

Mixed Review p.314