GCSE›Edexcel GCSE Maths›Mind mapsExpressions, Equations and IdentitiesEdexcel GCSE Maths: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsNotationababab means a×ba \times ba×b3y3y3y means y+y+yy + y + yy+y+ya2a^2a2 means a×aa \times aa×aCoefficient: the number multiplying a variableFour wordsExpression: no equals signEquation: true for specific valuesFormula: links two or more variablesIdentity (≡\equiv≡): true for every valueSimplifyLike terms: same letters, same powers5x+3y−2x+y=3x+4y5x + 3y - 2x + y = 3x + 4y5x+3y−2x+y=3x+4yUnlike terms stay separateAlgebra basicsexpressions and identities3y3y3y≡\equiv≡SubstituteReplace letters, then evaluatea=4a = 4a=4, b=−2b = -2b=−2: a2+3b=10a^2 + 3b = 10a2+3b=10Use brackets for negativesWorks for formulae such as v=u+atv = u + atv=u+atProve identitiesStart with the complicated sideExpand, then collect like terms2(x+3)+x=3x+62(x+3) + x = 3x + 62(x+3)+x=3x+6Exam tips3y≠y33y \ne y^33y=y3(−2)2=4(-2)^2 = 4(−2)2=4 but −22=−4-2^2 = -4−22=−4Simplify each side, do not move terms across ≡\equiv≡