Algebra 1Chapter 5Standard form, point slope form, and slope interceptPerpendicular lines
Standard FormMust write the equation in the form Ax+By=CFind 2 points on the line whose coordinates are both integersUse the values of the coordinates to fine the slope of the line using the formula m=y2-y1/x2-x1
Standard Form Cont….Use values found for slope and a coordinatesThen write it in point-slope form y-y1=m(x-x1)Solve for y
Standard Form Cont….Example:M= 5, (6,3)Y-3=5(x-6)     Write equationY-3=5x-30      Distribute the 5Y=5x-27         Add 3 to both sides
Standard Form Cont….Then to make it into standard form we may need to add or subtract from either sideExample:Y=5x-27         Add 27 to both sidesY+27=5x        Subtract y from both sides27=5x-yThis is in Standard Form
RecapPoint-slope form			y-y1=m(x-x1)Standard FormAx+By=CSlope formulam=y2-y1/x2-x1
Slope Intercept FormAn equation of the line with slope m and y-interceptTo find y-intercept, find where the point crosses the y-axis or where x=0It’s the y-intercept of that point Ex: (0,5) so the intercept is 5
Slope Intercept Form Cont….Then use slope formula m=y2-y1/x2-x1Use the point that you found for the y-interceptThen find another point whose coordinates are integers
Slope Intercept form Cont….Once you have found the y-intercept Also once found the slope Plug each one into the formula y=mx+b in the correct places
Slope Intercept Form Cont….Example:			Given points (0,6) (3,12)Find the slope and the y-interceptM=12-6/3-0=6/3=2Plug into y=mx+b
Slope Intercept Form Cont….Use the point that crosses the y-axisM=2, y-intercept=6			y=2x+6Remark: positive slope rises left to right, negative slope falls left to right
Perpendicular LinesTo find a line perpendicular to anotherFirst we need to know the slope of the first linePerpendicular lines have the opposite reciprocal of the normal line
Perpendicular Lines Cont…Once found the slope of the perpendicular lineUse the point slope equation to find the equation of that lineThen solve for y and put in slope intercept form
Perpendicular Lines Cont….Example:		Given two points (5,10) (8,16)Find the equation of the normal and perpendicular First: Find the slope of the normal line
Perpendicular Lines Cont….M=16-10/8-5=6/3=2Plug into point slope to find equation of the normal line, pick either pointM=2 (5,10)		y-10=2(x-5)		y-10=2x-10		y=2x
Example Cont….Now find the perpendicular lineThe slope is opposite and the reciprocal  of the normal M=-1/2, then just pick a point again and plug it into point slope formula
Example Cont….M=-1/2, (5,10)Y-10=-1/2(x-5)Y-10=-1/2x+5/2Y=-1/2x+25/2Now we have both equations

Algebra 1 Lesson Plan