IGCSE›Cambridge IGCSE Maths›Mind mapsLinear GraphsCambridge IGCSE Maths: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsEquationy=mx+cy = mx + cy=mx+cmmm is the gradient (steepness)ccc is the y-intercept (where x=0x = 0x=0)Rearrange ax+by=cax + by = cax+by=c to find mmm and cccGradientChange in yyy over change in xxxm=y2−y1x2−x1m = \frac{y_2-y_1}{x_2-x_1}m=x2−x1y2−y1(1,3)(1,3)(1,3) and (4,9)(4,9)(4,9) give m=2m = \mathbf{2}m=2Finding equation Find the gradient mmm Substitute a known point to find ccc Write as y=mx+cy = mx + cy=mx+c Through (2,7)(2,7)(2,7) with m=3m=3m=3: y=3x+1y = 3x + 1y=3x+1Linear graphsstraight linesmmmcccParallelParallel lines have the same gradientParallel to y=4x−1y = 4x - 1y=4x−1 has m=4m = \mathbf{4}m=4PerpendicularGradients multiply to −1-1−1m2=−1m1m_2 = -\frac{1}{m_1}m2=−m11Perpendicular bisector: through the midpointExam tipsKeep the order of subtraction consistent for the gradientPerpendicular: flip and negate the gradient