Between all points the slope(=(y2-y1)/(x2-x1)) has to be the same: first graph: [-5,-3] has a slope of 0.5, [-1,1] has a slope of 2 -> not a linear function second graph: [-4,-3] has a slope of -3, [-3,-2] has a slope of -1 -> not a linear function third graph: slope matches for all subsection->is a linear function fourth graph: [-4,-3] has a slope of +1, [-3,-2] has a slope of +2 -> not a linear function
-> the third graph is the only given linear function
