4MA0 Higher January 2013 Paper 3 Q18

EdexcelHigherOld spec7 marksDifferentiation

(a) Differentiate with respect to \(x\)

(i) \(8x^2\)

(ii) \(\dfrac{2}{x}\)

(3)

(b) The curve with equation \(y = 8x^2 + \dfrac{2}{x}\) has one turning point.
Find the coordinates of this turning point.
Show your working clearly. (4)

Scheme	Marks
(i) \(16x\)	B1
(ii) \(2x^{-1}\)	M1
\(-2x^{-2}\) oe	A1
	(3)

Scheme	Marks
\(\text{“}16x\text{”} + \text{“}{-2/x^2}\text{”} = 0\)	M1
\(16x = 2/x^2\) \(x^3 = 1/8\)	M1
\(x = \tfrac{1}{2}\) Answer: (½ , 6)	A1, A1
	(4)

Notes