bkevil Slope-Intercept Form of a Linear Equation y = mx + b
bkevil y = mx + b This is called the slope-intercept form of a linear equation because: You can see the slope (m)(m) You can see the y-intercept (b) (0, b)b) x and y represent all the (x, y) order pairs that graph points In this form the function can be easily graphed on the calculator.
bkevil Give the slope and y-intercept of each: 1.y = -2x y = x x + 3y = x – 2 = y 5. y = 2 6. x = -3 m = -2 (0, 1) m = 1 (0, 5) m = -2 / 3 (0, 3) m = -6 (0, -2) m = 0 (0, 2) This equation cannot be put into slope intercept form – slope is undefined & no y-intercept
bkevil x y Graphing a Line Using Slope-Intercept Form y = 3x st Put equation into y=mx + b form 2 nd Plot y-intercept (0, -2) 3 rd Count slope --- rise 3, run 1 and plot more points 4 th Draw the line y = 3x - 2
bkevil x y Graph Using Slope-Intercept 1 st Equation is in y=mx + b form 2 nd y-intercept = 3 Plot (0, 3)3) 3 rd slope = m= -1 / 2 -- rise -1, run 2 and plot more points 4 th Draw the line
bkevil Go to y1=y1= Type in equation Check out graph on the Calculator Set window Graph
bkevil y x Write an equation for the graph: Eq: y = mx + b Count slope between two points: m= -3 / 2 Identify y-intercept: b= 1 (0,1) Substitute values for m and b into equation: Eq: y = -3 / 2 x + 1 (0,1) Eq: y = -3 / 2 x + 1
bkevil Write the Equation of a line given– slope & y-intercept y = x + 1 st Write equation into y=x + form 2 nd Plug in slope m ( coefficient of x) 3 rd Plug in slope b ( y coordinate of pt. (0, b) 4 th Equation is in slope intercept form y = -½x + 5 Given: point (0, 5) & slope m = -½ Write the equation of the line. -½ y = x + 5 m b
bkevil Write the Equation of a line given– slope & a point y = x + 1 st Write equation into y=x + form 2 nd Plug in slope m ( coefficient of x) 3 rd Plug x and y from the given point 5 th Plug m & b into y=x + Given: point (-2, 5) & slope m = -3 Write the equation of the line. -3 y = x + b m b 5 = -3 (- 2 ) + b 5 = 6 + b -1 = b 4 th Solve for b y = -3x - 1
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