Warm Up
To be able to write a linear equation. Today’s Objective To be able to write a linear equation.
y = mx + b Slope-intercept form of the equation: Recall #1 Slope-intercept form of the equation: y = mx + b m is slope and b is the y-intercept.
Recall #1 y = mx + b y = 3x + 2 3 is slope and 2 is the y-intercept.
Y = 3x + 2 Slope = 3/1 Y y-intercept X
Recall #2 Slope Formula: m = y2 - y1 x2 - x1
(1, 4) and (2, 3) (x1, y1) & (x2, y2) m = 3 - 4 2 - 1 Recall #2 Slope Formula: m = y2 - y1 x2 - x1
Recall #2 m = 3 - 4 2 - 1 m = -1 1 m = -1
Write a linear Equation If f(2) = 5 and f(6) = 3 f(2) = 5 when x =2 & y = 5 (2,5) f(6) = 3 when x = 6 & y = 3 (6,3)
(2,5) & (6,3) When x = 2, f(x) = 5 f(x) When x = 6, f(x) = 3 X
(2, 5) and (6, 3) (x1, y1) & (x2, y2) m = 3 - 5 6 - 2 Step 1 find the slope (2, 5) and (6, 3) (x1, y1) & (x2, y2) m = 3 - 5 6 - 2 Slope Formula: m = y2 - y1 x2 - x1
Step 1 find the slope m = 3 - 5 6 - 2 m = -2 4 m = -1/2
y = mx + b (2,5) and (6,3) 5 = -1/2(2) + b 5 = -1 + b 6 = b Step 2 y = mx + b y = mx + b (2,5) and (6,3) 5 = -1/2(2) + b 5 = -1 + b 6 = b
y = -1/2x + 6 is the equation of the line. Finish If m = -1/2 and b = 6, then: y = -1/2x + 6 is the equation of the line.
Y = -1/2x + 6 f(x) X
Your Turn Write an equation of the line for: f(2) = -2 and f(-4) = 1 Step 1 find the slope Step 2 use y = mx + b to find the b value.
f(2) = -2 and f(-4) = 1 (2, -2) and (-4, 1) Slope = y2 - y1 x2 - x1 Step 1 find the slope f(2) = -2 and f(-4) = 1 (2, -2) and (-4, 1) Slope = y2 - y1 x2 - x1
(2, -2) and (-4, 1) Slope = 1 - -2 -4 - 2 Slope = 3 -6 Step 1 find the slope (2, -2) and (-4, 1) Slope = 1 - -2 -4 - 2 Slope = 3 -6 m = -1/2
y = mx + b (2,-2) and (-4,1) -2 = -1/2(2) + b -2 = -1 + b -1 = b Step 2 y = mx + b y = mx + b (2,-2) and (-4,1) -2 = -1/2(2) + b -2 = -1 + b -1 = b
y = -1/2x + -1 is the equation of the line. Finish If m = -1/2 & b = -1, then: y = -1/2x + -1 is the equation of the line.
Classwork See Side Board