IGCSE›Cambridge IGCSE Maths›Mind mapsAlgebra ToolkitCambridge IGCSE Maths: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsWhat letters meanA letter is a variable, a generalised numberExpression: no equals sign, e.g. 3x+53x + 53x+5Equation: two expressions equal, 3x+5=113x + 5 = 113x+5=11Formula: links different letters, A=lwA = lwA=lwSubstitution Write out the expression Replace letters, using brackets Calculate using BIDMAS a=3,b=−2a = 3, b = -2a=3,b=−2: 2a2−b=2(3)2−(−2)=202a^2 - b = 2(3)^2 - (-2) = 202a2−b=2(3)2−(−2)=20Algebrathe basic toolkitnnn2n2n2n3x+53x+53x+5Like termsSame letters and same powers3x3x3x and 5x5x5x are like; 3x3x3x and 3x23x^23x2 are notAdd or subtract the coefficients2a+3b+5a−9b=7a−6b2a + 3b + 5a - 9b = 7a - 6b2a+3b+5a−9b=7a−6bWords to algebra"2 more than nnn" is n+2n + 2n+2"3 less than nnn" is n−3n - 3n−3"Double nnn" is 2n2n2n£3 fee plus £5 per hour: C=3+5hC = 3 + 5hC=3+5hExam tipsBracket negatives: (−2)2(-2)^2(−2)2, not −22-2^2−22x2+3xx^2 + 3xx2+3x cannot be simplifiedWrite 'let nnn = ...' to earn method marks