Exercise 6 Page 123

Equations in slope-intercept form follow a certain format. y=mx+ b In this format m is the slope and b is the y-intercept. The line has a slope of 4 which means that we can substitute m=4. y=4x+ b To write a complete equation for this line, we also need to determine the y-intercept b. We can do that by substituting the given point (- 1,5) into the equation and solving for b.

y=4x+b

SubstituteII

x= - 1, y= 5

5=4( - 1)+b

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Solve for b

MultPosNeg

a(- b)=- a * b

5=- 4+b

AddEqn

LHS+4=RHS+4

9=b

RearrangeEqn

Rearrange equation

b= 9

Now that we have both the slope and the y-intercept, we can write the final equation. y=4x+ 9