# Math - Precalc

 .remove_background_ad { border: 1px solid #555555; padding: .75em; margin: .75em; background-color: #e7e7e7; } .rmbg_image { max-height: 80px; } General Form of equation of a line Ax+By=C Slope (steepness) Formula m= y2-y1 x2-x1m= rise = vertical change run horizontal change How do you read the graph? Left to right Rising m>0 positive Falling m<0 negative, hence y=b Horizontal zero (m=0) hence y=b Vertical Undefined, hence x=a Slope intercept form equation y=mx+b slope = m coordinate y= b How do we write the equation for slope intercept form? Isolate y variable so that it is y= slope (x) + b from given equation What is the y-intercept always equivalent to? the y coordinate Point slope formula Used if you have only one point and the slope y-y1=m(x-x1) (does not work for verticle lines) How do you find the equation of a line given 2 points? Use the points to find the slope, and then plug it into the point-slope formula How do you tell if lines are parallel They must have the same slope m1=m2 How do you find the equation of a parallel line? 1) write slope intercept form2) identify the slope given (parallel lines have same slope) 3) substitute slope into equation of the line4) substitute in variables (coordinates given) 5) since b is the only variable left, SOLVE FOR B What is unique ( and always true) about perpendicular slopes? The slopes' of the two lines will always be negative reciprocals of eachother Which two types of lines do not share the perpendicular slope property? horizontal, m=0vertical, slope undefined How do you find the equation of a perpendicular line? 1) Identify the slope of the given line 2) identify its reciprocal to find the slope that is perpendicular to given line3) Write equation of the line we are looking for in slope-intercept form y=m2x+b4) substitute the reciprocal slope back into equarion5) plug in coordinates6) since b is the only variable left, SOLVE FOR B .remove_background_ad { border: 1px solid #555555; padding: .75em; margin: .75em; background-color: #e7e7e7; } .rmbg_image { max-height: 80px; } AuthorJense133 ID71888 Card SetMath - Precalc DescriptionLines Updated2011-03-10T01:13:44Z Show Answers