document.write( "Question 1127518: Through (-6, 8); perpendicular to 9x + 5y = 66. Write the equation in y = mx + b form. Please show all work. \n" ); document.write( "
Algebra.Com's Answer #743930 by greenestamps(13216) You can put this solution on YOUR website! \n" ); document.write( "Any line parallel to 9x+5y=66 will have an equation of the form 9x+5y=C, where C is some constant; any line perpendicular to 9x+5y=66 will have an equation of the form 5x-9y=C (switch the coefficients and change the sign of one of them). \n" ); document.write( "So in your problem, an equation of the line you want is 5x-9y=C; the constant C is determined by using the coordinates of the given point. \n" ); document.write( "5(-6)-9(8) = -30-72 = -102 \n" ); document.write( "An equation of the line you are looking for is \n" ); document.write( "5x-9y = -102 \n" ); document.write( "In slope-intercept form.... \n" ); document.write( "9y = 5x+102 \n" ); document.write( "y = (5/9)x + 102/9 \n" ); document.write( "or \n" ); document.write( "y = (5/9)x + 34/3 \n" ); document.write( "If you are supposed to find the solution using basic algebra, then \n" ); document.write( "(1) put the given equation in slope-intercept form to find its slope; \n" ); document.write( "(2) find the slope of the line perpendicular to the given line; and \n" ); document.write( "(3) use the given point to find the y-intercept \n" ); document.write( "(1)... \n" ); document.write( "9x+5y = 66 \n" ); document.write( "5y = -9x+66 \n" ); document.write( "y = (-9/5)x+66/5 \n" ); document.write( "(2)... the perpendicular slope is 5/9, the equation is y=(5/9)x+C \n" ); document.write( "(3)... \n" ); document.write( "8 = (5/9)(-6)+C \n" ); document.write( "8 = -10/3+C \n" ); document.write( "C = 8+10/3 = 34/3 \n" ); document.write( "The equation (as found earlier by the other method) is \n" ); document.write( "y = (5/9)x + 34/3 \n" ); document.write( " \n" ); document.write( " |