Edexcel IGCSE Math A 2.3.HA Advanced Formula Rearrangement

Practise changing the subject when it appears twice, is squared or occurs within fractions on both sides.

Exam points

[Maximum number: 4]

Make r the subject of $m=\sqrt{\frac{6 a+r}{5 r}}$

$m^2=\frac{6a+r}{5r}$ $5rm^2=6a+r$ $5rm^2-r=6a$ $r(5m^2-1)=6a$

Final answer:
$r=\frac{6a}{5m^2-1}$

Equivalent form:
$r=\frac{-6a}{1-5m^2}$

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