Easy -1.2 This is a straightforward differentiation question requiring only basic power rule application after rewriting terms as powers (x^{1/2} and 3x^{-1}). It's simpler than average A-level questions as it involves no chain rule despite the topic label, just direct term-by-term differentiation with standard index notation.
no marks for use of Chain Rule or any other attempt to differentiate
\(\text{grad} = \frac{\sqrt{9.2} - \sqrt{9}}{4.1 - 4}\) soi
M1
SC2 for 0.33... appearing only embedded in equation of chord
\(0.3315\) cao
A1
Question 7(ii):
Answer
Marks
Guidance
selection of value in \((4, 4.1)\) and \(4\), or of two values in \([3.9, 4.1]\) centred on \(4\)
M1
allow selection of 4 and value in \((3.9, 4)\)
answer closer to \(\frac{1}{3}\) than \(0.3315\)...
A1
## Question 7(i):
$m = \frac{\sqrt{1 + 2 \times 4.1} - \sqrt{1 + 2 \times 4}}{4.1 - 4}$ soi | M1 | no marks for use of Chain Rule or any other attempt to differentiate
$\text{grad} = \frac{\sqrt{9.2} - \sqrt{9}}{4.1 - 4}$ soi | M1 | **SC2** for 0.33... appearing only embedded in equation of chord
$0.3315$ cao | A1 |
## Question 7(ii):
selection of value in $(4, 4.1)$ and $4$, or of two values in $[3.9, 4.1]$ centred on $4$ | M1 | allow selection of 4 and value in $(3.9, 4)$
answer closer to $\frac{1}{3}$ than $0.3315$... | A1 |
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