WAEC 2023 · Paper 1 · Q14

Expressions, formulae & change of subject

Make $x$ the subject of the relation $y = \dfrac{ax^3 - b}{3z}$ .

Worked solution (try it first)

Multiply both sides by $3z$ : $3yz = ax^3 - b$ .
Add $b$ and divide by $a$ : $x^3 = \frac{3yz + b}{a}$ .
Take the cube root: $x = \sqrt[3]{\dfrac{3yz + b}{a}}$ , option B.

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