Given any cubic or quartic equation with real coefficients, it can be transformed by a change of variable into a standard form, and thus solved by means of a double-sided scale (Fig. 1) in the case of ...

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For tips on how to do this, look at Factorising quadratics and Factorisation of further quadratics in this guide. For (\({x}\) + 2)(\({x}\) + 7) to equal 0 either the first or second bracket must be ...

Given any cubic or quartic equation with real coefficients, it can be transformed by a change of variable into a standard form, and thus solved by means of a double-sided scale (Fig. 1) in the case of ...