Unit 3 - Writing equation of a line (slope-intercept form)

y = mx + b

y = (1/2)x + b

Substitute the values for x and y into the equation. Solve for b (y-intercept).

5 = (1/2)(2) + b

5 = 1 + b

4 = b, or b = 4

Rewrite the equation in slope-intercept form. y = 1/2(x) + 4.

y = mx + b

y = 7x + b

Substitute the ordered pair (1,2) in place of x and y.

2 = 7(1) + b, Solve for b.

2 = 7 + b, Subtract 7 from each side.

2 - 7 = -5, b = -5

y = 7x - 5, check algebraically or using desmos!

y = mx + b

y = -1x + b

Substitute the ordered pair (3,-1) in place of x and y.

-1 = -1(3) + b, solve for b.

-1 = -3 + b, add 3 to both sides.

-1 + 3 = 2, b = 2

y = -x + 2 OR y = -1x + 2

y = mx + b

y = -4x + b

5 = -4(-2) + b

5 = 8 + b

5 - 8 = -3, b = -3

y = -4x - 3

Check algebraically or graphically using desmos!

y = mx + b

y = -1x + b

-4 = -1(2) + b

-4 = -2 + b

- 4 + 2 = -2, b = -2

y = -x -2 OR y = -1x - 2

Check algebraically or graphically using desmos!