Moderate -0.3 This is a straightforward implicit differentiation question requiring application of the product rule and chain rule, then substitution of given coordinates. It's slightly easier than average as it's a standard technique with clear steps and no conceptual surprises, typical of a first question on a C4 paper.
Substitute (1,2) into their differentiated equation and attempt to solve for \(\frac{dy}{dx}\)
M1 dep at
Or attempt to solve their diff equation for \(\frac{d\phi}{dx}\)
[Allow subst of (2,1)] least 1 x B1 and then substitute (1,2)
\(\frac{dy}{dx} = -2\)
A1
4
$\frac{d}{dx}(xy) = x\frac{dy}{dx} + y$ | B1 | s.o.i. e.g. $2x\frac{dy}{dx} + y$
$\frac{d}{dx}(y^2) = 2y\frac{dy}{dx}$ | B1 |
Substitute (1,2) into their differentiated equation and attempt to solve for $\frac{dy}{dx}$ | M1 dep at | Or attempt to solve their diff equation for $\frac{d\phi}{dx}$
[Allow subst of (2,1)] least 1 x B1 and then substitute (1,2) | |
$\frac{dy}{dx} = -2$ | A1 | 4
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