sat-dog

= + Choice C is correct. An equation of a line can be written in the form y mx b, ( ) where m is the slope of the line and 0, b is the y-intercept of the line. The line ( - ) =- shown passes through the point 0, 8 , so b 8. The line shown also passes (- ) through the point 8, 0 . The slope, m, of a line passing through two points ( 1 x, 1 y ) ( and - ( ) 2 x, 2 y ) ( c - an be ) calculated us = ing (- t 8 h )- e 0 equatio = n - m =y x 2 2 - - y x1 1. For th - e points 0, 8 and 8, 0 , this gives m -(- ), or m 1. Substituting 8 for 0 8 - = + = - (+ -) ( ) =- - b and 1 for m in y mx b yields y 1 x 8 , or y 8x. Therefore, =- - an equation of the graph shown is y 8x. - - Choice A is incorrect. This is an equation of a line with a slope of 2, not 1. - Choice B is incorrect. This is an equation of a line with a slope of 1, not 1. - Choice D is incorrect. This is an equation of a line with a slope of 2, not 1.