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Rearranging Formulae

Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.

Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.

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Mathematics · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)

Summary

The subject is the letter standing by itself. To change the subject you use inverse operations to peel everything else away.

Add, subtract, multiply, divide, square or square-root both sides equally. The equation stays true the whole way.

In v = u + at, t was multiplied by a then u was added. To free t, undo the addition first, then the multiplication.

From ax + b = cx + d: collect the x terms (ax − cx = d − b), factorise (x(a−c) = d−b), divide (x = (d−b)/(a−c)).

Hard words & meanings

subject of a formulathe variable written alone on one side, in terms of the others
rearrangeto use inverse operations to make a different variable the subject
inverse operationthe operation that undoes another, e.g. ÷ undoes ×
transposeanother word for rearranging a formula
factorise outto take a common letter outside a bracket, e.g. ax + ay = a(x + y)
denominatorthe bottom of a fraction; clear it by multiplying both sides
literal equationan equation built mostly of letters standing for real quantities
isolateto leave a variable alone on one side
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