Manipulating Formulae/ Changing the Subject: Eduqas GCSE Higher November 2017 Paper 1 Q13

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Higher November 2017 Paper 1 Q13

13. Rearrange the formula\[y = \frac{5 + x}{w - 2x}\]to make \(x\) the subject. [5]

Mark scheme

Scheme	Marks	Comments
\(y(w - 2x) = 5 + x\)	M1	FT until second error. Correctly clears the fraction.
\(wy - 2xy = 5 + x\)	M1	Multiplies out.
\(wy - 5 = x + 2xy\) or equivalent	M1	Collects \(x\) terms to one side.
\(wy - 5 = x(1 + 2y)\)	M1	Factorises
\(x = \dfrac{wy - 5}{1 + 2y}\)	A1	Divides Final answer; must be \(x = \ldots\) not \(-x = \ldots\)
	(5)